At least one centre-back, a central midfielder and a centre-forward are believed to be targets for the 20-time English champions, who finished down in eighth spot in last season's Premier League table.
Man United have famously previously raided Sporting Lisbon for huge talent, with Cristiano Ronaldo, Nani and Bruno Fernandes making moves to Old Trafford from the Portuguese giants.
Here, Sports Mole discusses the futures of three current Sporting stars who could potentially make the switch to Erik ten Hag's side this summer.
Goncalo Inacio (centre-back)
Raphael Varane is leaving Man United on a free transfer at the end of the month, while Victor Lindelof is also being heavily linked with a move away from the club, so it is possible that two new centre-backs could move to Old Trafford before the end of the summer transfer window.
The Red Devils are being heavily linked with Everton's Jarrad Branthwaite and Lille's Leny Yoro, but it is believed that the club are also keep on Sporting's Inacio.
The 22-year-old, who is currently with the Portugal squad at Euro 2024, made 50 appearances for Sporting during the 2023-24 campaign, scoring four goals and registering one assist in the process.
Inacio's release clause is believed to be €60m (£50.7m), which makes him an affordable target, and Liverpool are also thought to be keen on the Portuguese.
The defender came through the youth system at Sporting, and he has represented his current side on 171 occasions in all competitions, scoring 15 goals and registering nine assists in the process.
Morten Hjulmand (central midfielder)
Hjulmand was also in strong form for Sporting during the 2023-24 campaign, scoring five goals and registering four assists in 51 appearances in all competitions.
The 24-year-old was allegedly being tracked by Man United ahead of Euro 2024, but the speculation has increased since he scored a wonderful goal for Denmark against England last week.
Hjulmand's thunderbolt secured a point for Denmark, while his overall performance was excellent, with the midfielder demonstrating that he can compete at the highest level.
Man United could allow Casemiro and Christian Eriksen to both leave this summer, which would strengthen the club's need for a new central midfielder.
Hjulmand has a €80m (£67.6m) release clause in his current deal, with Sporting not thought to be willing to let him leave for under that figure.
Viktor Gyokeres (centre-forward)
Man United also need a centre-forward, with Rasmus Hojlund requiring some support next season, and the Red Devils are thought to be admirers of Gyokeres.
The 26-year-old was in excellent form during the 2023-24 campaign, scoring 43 goals and registering 15 assists in 50 appearances in all competitions, having arrived from Coventry City in July 2023.
Arsenal are also thought to be keen on Gyokeres, but Sporting are believed to be pointing to the €100m (£86m) release clause in the forward's contract.
The 20-time English champions will not be able to pay that amount for the Sweden international, but it is possible that the striker's asking price may drop down over the course of the summer.
Gyokeres's future is certainly a situation to keep an eye on, but for the moment, Man United have other targets, with Bologna's Joshua Zirkzee representing a cheaper option.