When Spain meet the Republic of Ireland in the pivotal Group C fixture on Thursday night, the spotlight will fall, as it always does, on the former Liverpool striker who cannot find the net. His travails are a source of increasing frustration. What Robbie Keane would do for a goal at the Arena Gdansk.

Keane, the Ireland captain, played with Fernando Torres at Liverpool for six months in 2008-09 and as a friend of the Spain striker he has always fought his corner when the bullets have flown in the Spaniard's direction. There was another hail of them after Torres spurned glorious chances in their 1-1 draw against Italy on Sunday here at the European Championship.

Yet it is Keane's form in recent matches that has led to uncomfortable questions, prominent among them the one to Giovanni Trapattoni, the Ireland manager, about whether he considers any of his players to be undroppable. It was asked with a gentle nod towards Keane, who has not scored in five games, which is his worst international sequence since he went eight matches without a goal from 2000-01. They are the only times that he has gone more than four games without an Ireland goal.

Keane is not always regarded as a predator or the consummate goalscorer, largely because there is so much more to his game, particularly his link-up work. But his international record would suggest otherwise and it marks him out as a legend before his time. The 31-year-old has 53 goals in 118 appearances; no other British or Irish player has passed 50 goals for his country. As such Keane's barren spell, which began in the second-leg of the play-off victory over Estonia last November and has taken in the friendlies against the Czech Republic, Bosnia-Herzegovina and Hungary, plus the opening Group C defeat against Croatia, is, at the very least, an irritation to him, even if he would never show it.

Few players did more than Keane to drive Ireland to their first major finals since 2002 – he scored seven times in qualification – and nobody appears prouder to wear the green shirt. He always talks of the admiration that he has for the supporters who sacrifice so much to follow the team, and the duty he feels to repay them, while he even fought the corner of the Irish journalists on the eve of the Croatia tie. The Uefa moderator at the pre-match press conference seemed to be ignoring them until Keane, from his position on the stage, stepped in to order him to allow their questions, saying that they ought to be paid the respect after following the team all the way from the first qualifier against Armenia in Yerevan. That got him a warm round of applause.

Keane's patriotism is so intense that any questions which relate to anything other than Ireland such as, whisper it, the Premier League, lead to frowns and prickliness. It means everything to him to lead Ireland and he was devastated by the 3-1 defeat to Croatia, which has left the team needing a result against Spain, the World and European champions, to stay alive. Ireland have not beaten opposition ranked above them by Fifa in a competitive game since 2001. Even the draw would feel like a miraculous result.

If Trapattoni's team did not perform to their capabilities against Croatia, then Keane was horribly peripheral and the subsequent inquiry chipped away at him. He noted, somewhat pointedly, that Ireland "didn't create many chances and you can only score goals when you get opportunities". The pressure on Keane's shoulders is nothing new but it is clear that he needs a big performance against Spain. One of only four Ireland survivors from the 2002 World Cup, it is conceivable that this could also be his last hurrah on the grandest stage.

Keane can count on Trapattoni's support. The Italian, always one to mix his languages, calls Keane "the capitain" and gave the impression he would always be the first name on his team-sheet. He referenced his "experience" and noted "you need strong players in this situation". Keane's credit rating is robust and he can feel untouchable.

Trapattoni broke from his habit and did not name his starting XI, but changes are expected to be minimal: Jon Walters or Paul Green could start for Kevin Doyle but little else is anticipated. The Italian is ever loyal and ever consistent. This was no time to tear up the blueprint that he has finessed for four years. He believes in the squad and in their capacity to dig out a shock result. "Anything is possible in 90 minutes," he said.

Keane's motivation is overwhelming.