The 35-year-old has rejoined Arsenal on a six-month deal.
Campbell left the Gunners on a free transfer, when his contract expired, to join Portsmouth in the summer of 2006.
“I have seen him in training and he is very sharp,” said Wenger. “His attitude is good, his talent is good. But it is the game which decides.
“It gives us the opportunity to have one more centre-back,” added the Arsenal boss. “Sol will give us experience, good advice and physically he has worked very hard.
“It is an opportunity for him to relaunch his career and for us it is a good help for the rest of the season. He is dedicated, motivated and looks happy to be back.”
