From the first day, the message was clear: keep calm and carry on. On 27 April, Pep Guardiola, appeared in the press room at the Camp Nou to announce that he was leaving at the end of the season. Sat among the journalists were a handful of Barcelona players but Lionel Messi was not one of them. He later said that he just couldn't be there: the emotion was too great. Barcelona's most successful coach was leaving, the man who symbolised the club better than anyone else, ever.

By the time the press conference was called, everyone expected Guardiola to walk. What they did not expect was for Sandro Rosell, the club's president, to announce at the same time that the new manager would be Tito Vilanova, until then Barcelona's No2.

Psychologically, the situation had been managed expertly. A crisis turned into a succession, a smooth transition. Guardiolismo without Guardiola? Continuity was the word. One Catalan columnist suggested that Tito could be Paisley to Guardiola's Shankly. "I was pleased when I heard the news," Messi said. "Tito was the first person to put me in the team. Until then I was a sub or didn't play at all."

Messi was talking about when he was 13. Vilanova was his coach in Barcelona's La Masia youth system. Gerard Piqué and Cesc Fábregas were among his team-mates. Vilanova became close friends with Guardiola when the two of them were progressing through La Masia themselves and together they spent four years coaching the first team. The season before that, they had coached Barcelona's B team together, managing players such as Pedro and Sergio Busquets.

Thierry Henry once called Vilanova Guardiola's "brother". They had the same vision. Vilanova's few interviews before this year revealed a man even more committed to their footballing identity than Guardiola.

Barcelona's vice-president this week admitted that Guardiola had been involved, with Vilanova, in preparing this season. In signing Jordi Alba, for example. Buying a central midfielder and employing him at centre-back has a familiar ring to it, too. On Sunday, Barcelona's central defenders against Real Madrid will be Javier Mascherano and Alex Song. Mascherano has adapted. Song, so far, has not.

"I don't think there will be big variations in the way that we do things. Every person, every coach, is different but we're expecting something similar," Andrés Iniesta said before the start of the season.

"I am not going to change things just for the sake of it," said Vilanova, who does not have the seductive quality of Guardiola. Nor, should results turn against him, does he have the mass appeal and power that facilitate resistance. But he is tough. "He is very direct. He doesn't mess around with stupid things," Xavi says. "Tito has surprised me. I knew he had personality but the leader was always Pep. Now he is a leader as well. As a No2 he didn't talk so much."

"They have different personalities," Messi says, "but the work is the same." This is backed up by Xavi: "The training sessions have not changed."

Under Vilanova, Barcelona have won six from six and already have an eight-point lead over Real Madrid. Victory on Sunday night in el clásico, the third already this season after the teams met in the Spanish Super Cup, won on away goals by Real, would open up a lead that borders on the decisive. It is early to say that, of course. Just as it is early too to draw conclusions about Vilanova. Not least because Barcelona's perfect start to La Liga has disguised the fact that it has been far from perfect. There has been a hint of vulnerability.

Barcelona still play a 4-3-3 based on possession and swift circulation of the ball. Statistics underline the similarities: under Vilanova Barcelona have so far completed an average of 696.8 passes per game, compared with 709 last season, with completion at 88.6% compared with 88.5%. They have scored 2.86 goals per game against 3.0 last season and taken 12.2 shots compared with 13.0. That control is about protection as well as penetration and they have faced 2.8 shots per game this season compared with 2.7 last year.

Vilanova has changed things; small details, nuances. Barcelona have appeared a little less elaborate and a little more direct, pushing a little higher up the pitch. Against Benfica on Wednesday they utilised the long diagonal to the left to open up the pitch and the only statistic that is markedly different between Vilanova's Barcelona and Guardiola's is the percentage of their passes played into the final third – 36.8% now, against 30.2% last season and 28.6% over the course of Guardiola's time. But then against Benfica the second-half orders were the opposite: Vilanova preached patience.

There have been other tweaks enforced and illustrated by injury and rotation. Following the international break, Vilanova left a jet-lagged Messi on the bench. Logical enough but rarely done before. Messi came on to win the game. Barcelona's 4-3-3 has been applied with two of the front three out wide, Vilanova using Cristian Tello where Guardiola opted for the currently injured Isaac Cuenca. It has also been applied with the team narrow and Fábregas advancing beyond Messi to create a system that has two centre-forwards – almost a 4-2-2-2.

Fábregas has scored three in his past two games; he had gone without a goal since February. Messi, meanwhile, played deeper and did not score against Sevilla or Benfica. He did, though, provide four assists. When behind, Vilanova has been swift to switch to 3-4-3. He has even used something similar to a 4-2-3-1. It has worked. Five times this season, Barcelona have trailed. In four, Vilanova intervened to change the game and secure victory. The fifth, however, was against Real Madrid.