Arsène Wenger has confirmed Manchester United have submitted a bid for Arsenal captain Thomas Vermaelen.
The 28-year-old is out of contract next summer and has already been the subject of a £10 million bid from Barcelona.
And ahead of the Gunners' Community Shield clash with Manchester City on Sunday, Wenger revealed United had made official contact.
Vermaelen has endured a forgettable 18 months at Arsenal
"Vermaelen could leave us because he needs to play now," Wenger re-emphasised. "We're in a position where it's difficult to stand in his way."
Of United's interest, the Frenchman added: "I think they could be in the group."
Wenger, however, would prefer to sell Vermaelen abroad and two years after former captain Robin van Persie signed for United he is understandably reluctant to allow another skipper to move north.
"Ideally we will sell him to a foreign club and it is an option for us," Wenger stressed. "We have offers from abroad as well."
Barcelona's Champions League participation - something United cannot offer - could work to their advantage. The Catalan club have already brought in Jeremy Mathieu for £20m from Valencia, as new coach Luís Enrique finally addresses their flimsy defence.
United, meanwhile, have reverted to a 3-5-2 system under Louis van Gaal yet possess just three first-team centre-backs following the departures of Nemanja Vidić and Rio Ferdinand.
The Red Devils remain interested in Borussia Dortmund's Mats Hummels however Vermaelen represents a cheaper, and admittedly inferior, option.