Arsenal boss Arsene Wenger admits Sunderland target Mathieu Debuchy is likely to leave the club this month.
The Black Cats are battling it out with Aston Villa for the signature of the French defender, who is desperate to keep his Euro 2016 hopes alive.
Sunderland have made a late move to pip Villa to the signing of Debuchy, with Allardyce still eager to strengthen his right-back options, as he has been throughout the January transfer window.
And Arsenal boss Wenger said: "Mathieu Debuchy might go somewhere but I don't know where.
"A decision has to be made quickly now."
Debuchy is keen to leave the Emirates to play regular first-team football and secure a place in the France squad for the summer’s European Championships, and Arsenal will not stand in the ex-Newcastle United man’s way.
But Sunderland will need to pip Villa to Debuchy’s signing after new boss Remi Garde has been pursuing his fellow Frenchman throughout the transfer window.
Sunderland have three right-back options available in the squad themselves, but the Black Cats have explored the possibility of terminating DeAndre Yedlin’s loan deal early in this window, while Adam Matthews could move to the Championship before Monday’s deadline.
Allardyce has seen two approaches for Lorient’s right-back Lamine Gassama turned down by the Senegal international, who was unwilling to join a relegation-threatened club, despite his contract in France due to expire this summer.
But the Sunderland boss has been on the look-out for players who need to find a new club for the remainder of this season, to ensure they don’t miss out on the Euro’s.
Debuchy - who joined Arsenal in a £12million move from Newcastle 18 months ago - is firmly in that category after the 30-year-old has fallen behind Hector Bellerin in the pecking order and hasn’t made a first-team appearance since November.