Manchester United and Arsenal have both been tipped to lure Lemar away from Monte Carlo this transfer window.
And the Red Devils’ path to the winger was left clear yesterday with Gunners boss Arsene Wenger conceding defeat in his bid to land the 21-year-old.
It represented a bitter blow to Arsenal fans, who had been hoping to see the 21-year-old move to the Emirates this summer.
But Castles says a Monaco contact has informed him Lemar would rather join United than their Premier League counterparts – and suggested it is why the Gunners have stopped pursing a deal.
“Arsene Wenger was asked about the Lemar deal, which is something Arsenal have pursued the whole summer, and he said it was dead as far as he was concerned,” he told the Transfer Window podcast.
“The argument he put was Monaco was dealing with the imminent departure to PSG and Fabinho, who is almost certain to join PSG as well and therefore would not be selling any more players.
“I had a chat with a Monaco contact last night, asking where things stood, he said the Lemar deal was very much on the table as far as they’re concerned.
“It is a possibility he leaves if the transfer fee they’re looking for (60m) is met.
“The interesting bit of information is I asked where Lemar would prefer to go, whether it’s Arsenal or Manchester United.
“And he was very clear. Lemar wants to go to Manchester United.
“That may be connected with Wenger’s statement in that, essentially, once United come in head to head with Arsenal the financial power is always gonna with the Old Trafford club and, this instance, the attraction of Champions League football.”
Lemar starred for Monaco as they won the Ligue 1 title last term.
Barcelona have also been linked with a move for the youngster but their deal for Ousmane Dembele suggests that pursuit is over.