Arsenal boss Arsene Wenger has said Cesc Fabregas is likely to be fit for Tuesday's Champions League last-16 second leg at Barcelona.
Wenger will be without a number of key players in the Nou Camp as the Gunners look to defend a 2-1 first-leg victory.
But of his captain, who has missed three games with a hamstring injury and faces a final fitness test on Monday, he said: "It is 90% he will be fit.
"His return is vital, he is important [linking] attack and defence."
In Fabregas' absence, Arsenal were held to a goalless draw at home by Sunderland on Saturday as they looked to put pressure on Premier League leaders Manchester United.
But while Wenger should be able to call on a player he referred to as "the leader of the team" for the first time since he went off injured against Stoke on 23 February, he faces a number of other selection headaches.
We do not have enough security to sit back and defend. You can't go to Barcelona, play for a 0-0 and not try to score
Arsene Wenger
Jack Wilshere has declared himself fit, despite picking up a knock on an ankle knock at the weekend but his midfield partner Alex Song is set to miss out with a knee injury. Wenger also has to do without winger Theo Walcott and striker Robin van Persie, who scored Arsenal's equaliser in the first leg.
Wenger confirmed: "Alex Song is completely out. He had a test on Sunday morning and it was negative. Wilshere will be fit.
"Everybody else who played on Saturday should be available."
Arsenal came up against an inspired Lionel Messi at the Nou Camp last season as the Argentina forward scored all four of his side's goals in a 4-1 win which gave Barcelona a 6-3 aggregate victory over the Gunners in the Champions League quarter-final.
To counter Messi, Wenger could deploy a defensive formation in Spain with Nicklas Bendtner in front of a five-man midfield with much resting on the performance of Samir Nasri.
However Wenger insisted his side would not be able to rest on their lead.
"We need some fresh legs for the Nou Camp because we will have to run a lot," Wenger explained.
"But we do not have enough security to sit back and defend. You can't go to Barcelona, play for a 0-0 and not try to score.
"It is also not the personality of this team.
"We will look to defend well and attack well. We are not a team that will refuse to attack, we know that.
"The challenge will be to find the right balance between having a team who can defend, as well as one that has a good opportunity, every time it has the ball, to go forward."
Barcelona's Javier Mascherano has warned his team-mates not to Arsenal.
"They are not stupid. They have an advantage and they will try to protect that lead. They will come to defend," said the former Liverpool midfielder.
"We can't make the mistake of thinking that, just because they know how to play attacking football, they don't know how to defend.
"The problem is that when they have the ball they will try to play football - because of the players and the coach they have."
Barcelona will be unable to field either of their first-choice central defenders, with captain Carles Puyol out with a knee injury and and Gerard Pique suspended.
Defensive midfielder Sergio Busquets is likely to partner Eric Abidal at centre-back for the three-time European champions but the loss of Spain captain Puyol will be felt keenly by the Catalan outfit.
"His character makes him the soul of this team," said full-back Dani Alves.
"With the quality we have we'll try to miss him a little less. But his qualities make him irreplaceable."
Meanwhile, Barcelona coach Pep Guardiola has been suffering his own injury problems.
The 40-year-old coach has a herniated disc in his back and will take training with the team on Monday before spending the night in hospital for treatment.
However, Guardiola is expected to be on the touchline on Tuesday.
