Mexican striker Carlos Vela has rejoined the Arsenal squad ahead of Wednesday's Champions League semi-final against Manchester United after spending a day in quarantine due to fears over the swine flu outbreak.
Vela, 20, was told to stay away from the Gunners' training session following a visit by some friends from Mexico, where more than 150 deaths have been blamed on the virus.
Mexico is the centre of the outbreak of the disease and Arsenal manager Arsene Wenger said: "It looked to be a massive problem because we were asked yesterday to keep him at home and not get him to the training ground."
"Now he has the all-clear and today he was free again to attend training."
Wenger added: "It was basically down to the fact he had visitors from Mexico, friends who came to visit him last week."
With strikers Robin Van Persie and Eduardo both injured Vela could well find himself on the bench for the European clash.
Meanwhile, Arsenal defender Kieran Gibbs is struggling with an ankle injury and is a major doubt for the match at Old Trafford. His likely replacement Mikael Silvestre is not certain to be involved either as he tries to shake off a back complaint.
Captain Cesc Fabregas (ankle/knee) and defender Johan Djourou (knee) also got through training on Tuesday morning but leading scorer van Persie (groin) and left-back Gael Clichy (back) remain sidelined, while Russian midfielder Andrei Arshavin is ineligible.