Leo Messi hit the bar, Andrés Iniesta hit the bar and Bojan Krkic hit the turf, crumpling to his knees, the ball somehow hitting the net. Jesús Navas headed home then headed up the wing, zooming on to the ball – "a Formula 1" said his coach. Five hundred and thirty kilometres away, José Mourinho's latest conspiracy theory was coming unstuck but he didn't care. Instead, he punched the air, delighted. Víctor Valdés saved the shot. "Sevilla, put your bollocks into it," they chanted. So Sevilla did. Gary Medel cleared off the line and dashed about biting people's ankles. Fernando Navarro and Martín Cáceres hurtled by, crashing into shins. Alvaro Negredo pulled on his helmet and went into war. The Arrebato rang out. The Sánchez Pizjuán Stadium shook.

Dani Alves took a death-defying leap into the unknown. Or the penalty area, as it's sometimes known. Didier Zokora tumbled too. So did Diego Capel, but that's hardly news. Xavi tiki-taka'd. Diego Perotti put down his textbooks and took up flight. Not far from where Messi had taken flight a bit before. Eric Abidal performed the greatest, and lowest, diving header ever. The referee, Miguel Angel Pérez Lasa, invented his own rules, each more bizarre than the last, and the Catalan media, which complained when its rivals' cried, started crying. The league title race reopened; it was breathless and brilliant. A proper game; tough, fast and intense. "A joy," as one newspaper put it. And everywhere you looked, everyone was screeching by. Well, almost everyone: amid the chaos one man glided, hardly blinking as he changed the game – and maybe even the destiny of the title.

Frédéric Kanouté.

They got the wrong man. At the start of the second half between Sevilla and Barcelona on Sunday, everyone was looking for Leo; they should have focused on Fredi. In the last minute of the first half, Messi tumbled over Javi Varas, hit the deck and stayed there. The half-time whistle went but Messi didn't move. They called for the stretcher; it looked serious, the image that terrified every Barcelona fan. Eventually, a little dazed, he got to his feet and ambled uneasily off the pitch but few expected him to continue. Pedro had already been replaced after 12 minutes but that was nothing compared to this. This was the moment the match turned, the moment the title did. Barcelona were 1-0 up and it should have been more. But could Barcelona really win the league without the Argentinian?

Fifteen minutes later, the teams emerged from the tunnel. Necks craned. And there he was: Messi. Hardly anyone even noticed that there was Kanouté too. Soon they would. They had breathed a huge sigh of relief; everything seemed sorted. Only it wasn't. Pep Guardiola was able to keep his team the same; Gregorio Manzano chose to alter his. Zokora made way and Kanouté came on. Four minutes later, he eased smoothly away from a tackle and slotted the ball calmly through the gap for Negredo, who dashed into the area, clipped the ball back and Navas scored. Suddenly, it was 1-1. Suddenly, it was a brilliant game, El País calling it "a night of heroes", a "toast to football". Barcelona's dominance was shaken: they continued to pass and create, and continued to get chances – lots of them – but now so too did Sevilla. Suddenly, unexpectedly, Sevilla were what Sevilla used to be: fun.

The change had come. Not with Messi staying on but Kanouté coming on. For Sevilla, there was pace and menace. Now, though, there was also someone to actually make it work, someone to give it sense and direction, control. "Few teams have taken the ball off Barcelona as much as us," Manzano said proudly. "This was two superpowers fighting it out," beamed the president, José María del Nido. On the night in which Sevilla bade adiós to Luís Fabiano – the striker who, almost without anyone noticing, left for Brazil on Thursday night, leaving behind six seasons and 72 league goals with a mobile phone picture of himself in a São Paulo shirt – it was that other key player in the greatest Sevilla side in history that made the difference.

"Kanouté," said Guardiola, "gave them the pausa they needed." Kanouté, said Santi Giménez in AS, "is a spectacular, elegant, stupendous player who turned the game round." It was classic Kanouté: smooth and skilful, never in a hurry. Intelligent and eloquent, strikingly mild for a sportsman, he's the striker, playmaker and footballer many Sevilla supporters think is the best signing they have ever made (Alves permitting); the man who gave over €300,000 (£260,000) to prevent a local mosque from closing and played with masking tape over the 888.com on his Sevilla shirt because he did not want to advertise a bookmaker. The man who scored in the Uefa Cup final in 2006 when Sevilla won their first major trophy in almost 60 years, he also got the winning goal in the Copa del Rey final and scored in the Uefa Cup final, the following season.

Kanouté is 6ft 3in and weighs 13½ stone. The pity has been that there was not always that little bit more of him. In 2006-07, he missed six games and started a further two on the bench but still scored 21 goals. In the campaign in which Sevilla won the Copa del Rey and the Uefa Cup as well, by the end he was running on empty. Sevilla went into the final day with a chance of winning the title but knowing that they probably wouldn't. It was a tragedy that they did not take the title: the last genuine challenge to the top two. What ultimately cost them were the eight 0-0 draws over the course of the season – six of which came in the last 18 matches and two of which Kanouté was absent for. In the others, he might as well have been.

Seeing Kanouté be brilliant but brittle is nothing new. But this is another step again. Kanouté is 33 now. It was no coincidence that he started on the bench; or that he has started fewer than half of Sevilla's games this season. He may not be able to give much more. This felt like a last waltz from a truly great player. And that's a huge challenge for the club. Like Alves, will they find him irreplaceable?

After years of unusually poor, wasteful signings and a coach that haven't convinced, you're left with the feeling that Sevilla's best players are still the ones who were already there: Kanouté, Navas and, until this week, Luís Fabiano.

Few of the new signings have had any real, lasting impact; fewer of the old players remain. Ivica Dragutinovic has virtually disappeared, Antonio Puerta of course died, even Andrés Palop is playing less, while Luís Fabiano, like Enzo Maresca, Alves, Christian Poulsen and Javier Navarro, has gone. Perotti hasn't quite taken the step up and Negredo is at turns brilliant and awful. In the past couple of weeks there have been signs that Sevilla may have finally found a solution: the arrival of Medel and Ivan Rakitic has given them greater presence and control in central midfield, releasing Kanouté from his role there. And yet if Sunday night was a throwback to what Sevilla were, it was also an indication of just how much they may miss Kanouté when he finally walks away. The question now is: when will that be?

In the meantime, best just to enjoy him. And this weekend it wasn't just the Sevilla fans enjoying him. "Kanouté," said a grateful Marca, "decides that there is a league title after all." "The league," it adds, "has been resuscitated by the grace of Kanouté: the title race is still alive!" On the weekend in which Mourinho said any more dropped points meant adiós for Real Madrid it was their rivals who dropped them: Barcelona's draw in Sevilla allowed Madrid to climb back to only five points behind Barcelona. Yes, screamed AS's cover: "FIVE POINTS!"

Better still, on the face of it, Barcelona's imperious form has slipped away in recent weeks. They have scored 79 goals this season but their past three league results read: 1-0, 1-0, 1-1. In two of their past four away matches they have drawn 1-1; they have won the other 12. On Sunday night Sergio Busquets's personal run of 25 successive league victories finally came to an end. Barça were running at three goals a game for the first 25 matches of the season; now it's one per match over the past three. No wonder Marca was busy pointing out that Madrid have recovered a gap this big before; no wonder AS was busy clinging to the Burning Nail – the biblical version of clutching at straws, the blind faith that implausibly paid off under Fabio Capello. The only thing that was lacking was the ever-charming crappingyourselfometer.

And yet Barcelona were not panicking. They beat Zaragoza only 1-0 but that game came immediately before the Champions League second leg against Arsenal; likewise, the 1-1 with Sporting Gijón came immediately before the first leg. The 1-0 win at Valencia was considered a huge success, not a slip, and as Sport was desperate to point out the 1-1 draw in Seville represents "a good point". Not least because Barcelona could point to extenuating circumstances: twice they hit the bar, they had a perfectly good goal mysteriously ruled out and had a penalty turned down (one that could have gone against them was ignored too). They are still creating chances: it could have ended 5-3 against Sevilla and then the discourse would have been different. Sure, it will worry them that, as Guardiola put it, "we are reaping less than we sow", but Barcelona's physical preparation plans for two peaks in the season: the first is November to December, the second is not due until early April.

When you look at the key games, too, Barcelona still have the advantage. The hardest trips are to Valencia, Sevilla, Villarreal and Athletic. Barcelona won in Valencia and Bilbao, and drew in Seville. They face Villarreal in two weeks' time. Madrid still have to go to all four. And although the advantage may be that they are their final four away games of the season – by which stage their opponents' objectives may be fulfilled, their competitive edge blunted – that represents an extremely difficult run-in. Before that Madrid have to travel to Atlético Madrid. Mind you, we all know what will happen there. And then there's the clásico on 20 April.

Barcelona slipped, the game turned by a gentle giant with a special gift, but this was no time to panic. Asked how his players were in the dressing room, Guardiola replied: "In the shower – there's hot water and everything."

Talking points

• Real Madrid won 2-0 against Hércules. And let's face it there's not much to add to that. Except that Karim Benzema is really, really good at the moment. Maybe you can hunt with cats too.

• "I have got a screw loose," said Sporting Gijón's Diego Castro, before falling about laughing. He took a 92nd-minute penalty against Villarreal, awarded for a spectacular dive from Nacho Novo, with his side 1-0 down and only two points above the relegation zone. And he decided to do a Panenka. Only he hasn't got a screw loose: there was method in his madness. "López covers a lot of the goal and I figured that in a situation like this, he was bound to move quickly and dive," he said. And so it proved. Cool as you like, the ball floated down the middle as Diego López dived out the way. Genius.

• Valencia's players apologised to their fans after their 4-0 defeat against Zaragoza. But it was always going to happen: knocked out of the Champions League by Schalke in midweek, they played the first game on Saturday evening having travelled back from Germany and arrived back shattered emotionally and physically. Zaragoza also desperately needed a win while Valencia now know that, with an 11-point cushion, their top-four finish is virtually guaranteed. The game's most striking moment came from Gabi, who told Jordi Alba, lying on the floor after an "encounter" with Ponzio, to "stop screaming or I'll stamp on your face".

• Caicedo didn't score. Levante, though, did. They have now lost only one in eight. Luis García, we salute you! Their place as Spain's team that are surely going to go down is now taken by Hércules – sadly for their noisy, committed fans.

Results: Espanyol 2-0 Deportivo La Coruña, Levante 1-1 Mallorca, Osasuna 3-1 Racing Santander, Real Sociedad 0-2 Málaga, Sevilla 1-1 Barcelona, Villarreal 1-1 Sporting Gijón, Almería 2-2 Atlético Madrid, Real Madrid 2-0 Hércules, Real Zaragoza 4-0 Valencia. Monday night: Getafe v Athletic Bilbao