Robin van Persie has unexpectedly been named in Arsenal's squad to face Barcelona on Tuesday after making an early return to training.
Pictures released on the club's official website showed Netherlands striker van Persie participating in full training on Monday morning, less than a week after Gunners boss Arsene Wenger ruled him out for a month with knee ligament damage.
Later that afternoon, van Persie's inclusion in a 19-man Arsenal squad was confirmed.
The Dutchman is travelling for the Champions League last-16 second-leg tie at the Nou Camp.
Van Persie was substituted during Arsenal's Carling Cup final defeat against Birmingham after suffering a knee injury while scoring the equaliser at Wembley.
The second leg was expected to come too soon for the Holland ace but he trained with his team-mates at London Colney on Monday and Wenger has included him in a 19-man squad that will be cut to 18 ahead of the match.
The Gunners, who lead 2-1 from the first leg at the Emirates, are confident captain Cesc Fabregas will be fit but Alex Song is ruled out by a knee injury.
Former Barca youth player Fabregas has not played since injuring his hamstring in the victory over Stoke almost two weeks ago and missed the Carling Cup final.
His recovery is going well, though, and he now looks likely to take his place at the Nou Camp.
"Fabregas will have a final test today," said Wenger on Monday morning. "It is 90% he will travel and be fit. It is vital for us because he is important in the transition between attacking and defending. He is also the leader of the team so we want him there."
Holding midfielder Song, who started the first leg, has not been so lucky but, as expected, Jack Wilshere has recovered from slight ankle discomfort.
"Alex Song is completely out. He had a test on Sunday morning and it was negative," said Wenger. "Wilshere will be fit.
"Everybody else who played on Saturday should be available."
