Arsenal's chances of beating defending champion Barcelona in the first leg of the Champions League quarterfinals on Wednesday could be severely dented before kickoff at Emirates Stadium.
Cesc Fabregas is Arsenal's leading scorer this season with a remarkable 18 goals in 35 matches from central midfield but he is receiving treatment to a knee injury and sat out training on Tuesday.
With coach Arsene Wenger having tweaked his formation to give the 22-year-old Spain international greater freedom in attack, his absence would leave a big hole against the club with the second-tightest defense in the competition.
Wenger has acknowledged the futility of trying to muscle and mark Barcelona out of the game, so Fabregas is arguably the key figure in the Gunners' efforts to outpass or outscore the Spanish team.
"At the moment he is not fit to play," Wenger said. "We will give Cesc 24 hours more and tomorrow we will assess the situation. It's too early to say.
"If he has full capacity tomorrow, I will play him. If the game was today, he would not play."
Fabregas has been having intensive treatment on the damage he sustained in Saturday's 1-1 English Premier League draw with Birmingham.
But Wenger said Fabregas will either start against Barcelona or not play at all, ruling out the possibility of introducing him as a late substitute.
"If he is not capable to play, I will not even put him on the bench," Wenger said.
Fabregas' ability to drift unmarked into attacking positions or carry the ball there himself would be missed, but maybe not as much as his composure in possession and accurate passing.
That's because the key to Barcelona's defensive success is the fact that other teams simply cannot get hold of the ball.
Barca has enjoyed 67 percent possession in its Champions League matches, with Bayern Munich a distant second of the eight remaining teams with 56 percent.
"Win or lose, I want us to show who we are and what kind of football we believe in," Barcelona coach Pep Guardiola said.
Emmanuel Eboue could come into the Arsenal side to stiffen a midfield that will be required to help out the defense against the devastating Lionel Messi and former Arsenal great Thierry Henry.
Messi was a teammate of Fabregas in the Barcelona youth teams before Fabregas opted to join Arsenal in 2003.
The Argentina striker is world and European player of the year and has four Champions League goals this season on top of the 25 he has in the Spanish league.
Former England defender Sol Campbell scored for Arsenal in its 2-1 loss to Barcelona in the 2006 final and will be up against Messi just two months after returning to top-class football.
"It is unbelievable," Wenger said. "He played at Notts County six months ago. That he can turn up and play against Barcelona is quite amazing."
Messi missed the 2006 final because of injury, while Henry played for Arsenal.
If Henry plays on Wednesday, it will be his first appearance against Arsenal at Emirates Stadium since leaving three years ago.
Barcelona will be without midfielder Andres Iniesta because of injury but defenders Eric Abidal and Gerard Pique should have recovered from injury to play.
