Experienced Arsenal defender William Gallas will miss tonight's Champions League clash with FC Porto.

The 32-year old Frenchman has been out for some time with the injury and was set to make a comeback at Emirates Stadium tonight but broke down in training and could be out for a further month according to Gunners boss Arsene Wenger.

"Gallas has been out for a month and now he has had a recurrence of his calf injury. He felt very well on Sunday and went out, but he has gone backwards again. We are back at the starting point with Gallas unfortunately," Wenger said.

"We don't know how long it will be. He will have a scan and we will assess it from there, but for Hull this weekend, for example, he has no chance.

"We were impatient with him and we pushed him and he wanted to get on as well, that is why maybe it has happened. But there is no obvious sign as to why it keeps coming back. He has no pain at all, then goes for a little jog and then it goes again."