Arsenal captain Cesc Fabregas has been ruled out of tomorrow's Champions League clash with Porto because of a hamstring problem.
The midfielder limped off after scoring the opening goal in the 3-1 Barclays Premier League victory over Burnley on Saturday.
The tightness was in the same hamstring he injured earlier in the season, which kept him out of action at the turn of the year.
Gunners boss Arsene Wenger said: "We cannot even take a gamble, so he is not available."
Veteran defender Sol Campbell did, however, join in training and he looks set to recover from a groin problem in time to face the Portuguese side, who will take a 2-1 lead to the Emirates Stadium for the second leg of the last-16 tie.