According to the Independent, the Red Devils have made inquiries with Watford over the availability of the Senegal international and could make him their second signing of the summer following Donny van de Beek's arrival.
Manchester United have identified the signing of Jadon Sancho from Borussia Dortmund as their number one priority for the summer but they have hit several roadblocks in their quest for the England international and have started considering alternatives.
Gareth Bale was among the players liked with a switch to Old Trafford but with the Welshman on his way to Tottenham, the Red Devils have now set their sights on Ismaila Sarr.
Impressive Ismaila Sarr on several clubs' radar
Ismaila Sarr was signed by Watford from French side Stade Rennais in August 2019 and in just one season in the Premier League, he sent a statement of intent with his quality.
The 22-year-old originally struggled to break into an out-of-sorts Watford side but following the appointment of Nigel Pearson in December, he started getting adequate gametime.
He was the standout performer as Watford initially climbed out of the relegation places, and a run of two goals and three assists helped the Hornets go unbeaten for six matches between December and January, picking up 14 from a possible 18 points.
Ismaila Sarr was the star of the show when Watford shocked Liverpool in a 3-0 defeat, ending the Reds' 42-game unbeaten run and he made Jurgen Klopp's defenders look like Sunday League footballers.
He weighed in with two goals and an assist in that memorable victory and also put Manchester United to the sword earlier in the season with a goal and assist in a 2-0 victory.
Although Watford ultimately got relegated, the former Metz man did enough to showcase his quality.
Ismaila Sarr is yet to make an appearance in any of his side's two matches this season as speculation continues to mount that he could be on his way out of the Championship.
It is believed that a fee of £30 million would be enough to prise him away from Vicarage Road but Manchester United would have to act fast to secure the services of the forward as Liverpool have also been linked with him.
Having already lost out on several of their key targets this summer, Ole Gunnar Solskjaer would be keen to finalise transfer proceedings in the coming weeks as he seeks to consolidate on the gains made in the last camp.