Manchester United would consider a move for Arsenal defender Thomas Vermaelen should they fail to sign Benfica centre-back Ezequiel Garay.
According to reports in Portuguese newspaper A Bola, Garay remains a key target for United boss David Moyes this summer.
But Russian side Zenit St Petersburg may beat United to the signing before Moyes gets another chance to snap him up - and that could bring the Arsenal player into the equation.
The Russian transfer window does not shut until the end of February, which means Zenit still have plenty of time to conclude a deal without competition from United.
After the Benfica versus Sporting Lisbon match earlier this week Benfica coach Jorge Jesus admitted that Garay's future is up to the player and the club's board.
But the report claims United have alternative targets should they lose the race for Garay, one of them being Arsenal's out-of-favour centre-half Thomas Vermaelen.
The Belgian international has been forced to watch from the bench as Arsene Wenger has picked Per Mertesacker and Laurent Koscielny as his regular defensive partnership.
Although playing time before the World Cup remains a priority for the ex-Gunners captain, he may be tempted to move after the tournament if his prospects at the Emirates Stadium do not improve.
United need defensive cover with Nemanja Vidic set to leave the club and Rio Ferdinand approaching the end of his career, and they could do worse than looking at the Arsenal centre-half.