The 24-year-old joined Leipzig from Dinamo Zagreb in 2020, and he has made 106 appearances for the Bundesliga outfit since.
The Spain international has scored 19 goals and registered 22 assists for the club in that time, including three goals and four assists in 14 matches across all competitions during the ongoing campaign.
However, the Spaniard has now entered the final 18 months of his contract with the German club and has only started seven top flight appearances this season.
Tottenham Hotspur, AC Milan and Real Madrid are also credited with an interest in the versatile playmaker, who could join the Red Devils as an alternative to Cody Gakpo.
The Mancunian giants fought hard to bring in Gakpo over the summer but have now lost out to Premier League rivals Liverpool for the signature of the Dutchman, who joined the Merseyside outfit from PSV Eindhoven.
A new attacker is still on the agenda for Man United leaving manager Erik ten Hag with Anthony Martial and Marcus Rashford as his two options in the middle of the pitch.