The former forward accepts that things may be difficult for the Argentine, though, as Louis van Gaal isn't a fan of South American players.
The Argentine suffered a poor first season in England following his big money move from Real Madrid last summer, finishing the campaign on the bench.
That was a disappointing way to end a Premier League stint which had started brightly enough for the winger, with reports now linking him with moves away from Old Trafford as it seems manager Louis van Gaal has given up on the player.
Forlan, though, says the Red Devils would regret selling him should he leave, believing he should be given another season in which to prove himself.
“United will regret it if he leaves,” he wrote in El Nacional.
“He should be given another season to prove himself and United should try to understand him better and trust him. Great coaches and great players don’t always get on and not every player fits into rigid systems, but Di Maria is worth persisting with.”
Van Gaal not a fan of South American players?
Forlan, though, concedes that there may be no way back for Di Maria at Manchester United, so long as Van Gaal is in charge anyway.
The Dutch manager seemed to lose patience with the club’s record signing last year as he continually failed to deliver for the side, with the former Real Madrid man ending up being limited to brief cameos from the bench come the season’s finale.
And Forlan suggests that Van Gaal has never been a fan of South American players, something which is likely to hinder Di Maria’s chances of staying at the club.
“Louis van Gaal has never been a fan of South American players, as my good friend Juan Roman Riquelme will tell you from his time under the Dutchman at Barcelona,” he added.
“[He] also had a habit of letting his South Americans leave when he was at Bayern Munich.”