The 19-time English champions have already had a bid rejected for the Brazil international this summer.
And the Ligue 1 outfit have now joined the race to sign the winger, although they are yet to make a concrete offer for the 19-year-old midfielder.
“We have been probed by PSG about Lucas,” Sao Paulo vice-president Joao Paulo de Jesus Lopes told France-based newspaper Le 10 Sport.
“[PSG director of football] Leonardo has a very good relationship with Sao Paulo. But for now nothing is definite.
“The possibility exists but it is down to the player’s interests. The policy of Sao Paulo is to follow the desires of the player.
“If the player wishes to leave, Sao Paulo will not create any obstacle. But we must receive a proposal that is appropriate.
“It’s a financial issue. Paris Saint-Germain is a big club in European football and if the player’s interests and also the club’s are met, I do not see why it would not happen.”
Sir Alex Ferguson confirmed United’s interested in signing Lucas back in July but the 70-year-old admitted the two clubs were yet to reach an agreement for the winger.
“We haven’t reached an agreement for the player,” he said. “We’ve shown an interest but until such time as we get a deal agreed we can’t say he’s our player.”
Lucas has scored 26 goals in 104 appearances for Sao Paulo since making his debut for the Brazilian outfit in 2010.
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