The story reveals United boss Sir Alex Ferguson's determination to add to an apparent lack of depth in the position.
"With Ferguson having finally concluded a deal for Robin van Persie, the manager is understood to have become a little perturbed again about the fact that an already overplayed Patrice Evra is United's only real option at left-back."
Since letting Brazilian defender Fabio go out on loan to fellow Premier League club QPR, Evra remains the only player naturally capable of playing at left full-back.
At the press conference to unveil new signing Robin van Persie Friday, Sir Alex hinted that the club could make another splash in the transfer market if "a certain player came available."
An offer in excess of £10 million would need to be made if Everton manager David Moyes is to be persuaded to part with Baines.
It is widely known that Baines has been a top target for the Red Devils this summer, but with over £40 million having already been spent on transfers, some had speculated that their spending was concluded.
But this appears not to be the case, as Sir Alex attempts to put together a team capable of challenging not just for domestic honours, but for European ones as well.
United kick off their season Monday night in a difficult away fixture at Everton, where high-profile new signings Shinji Kagawa and Robin van Persie are expected to make their eagerly awaited debuts.