The Scotland international could become a free agent at the end of the 2024-25 season as things stand, putting Man United in a complicated situation regarding his future.
As McTominay is in the last 12 months of his contract, the summer transfer window likely represents the Red Devils' last chance to recoup a sizeable fee for his services if he does not extend.
The 27-year-old was a crucial player for Erik ten Hag last season with 10 goals and three assists in 43 matches, but he has never cemented a regular starting role in the Red Devils' midfield.
Last week, it was reported that Fulham had tested the waters with a bid for the Scotsman, which was rejected by Manchester United, and Tottenham Hotspur have now entered the race too.
Man United 'want £30m' to sanction McTominay sale
The Lilywhites are in the market for a new midfielder, as Pierre-Emile Hojbjerg is reportedly on the brink of joining Marseille, while Tanguy Ndombele has also had his deal terminated.
Turkish outfit Galatasaray have also expressed an interest in McTominay, and according to Football Insider, the interested parties have been told that it would take a £30m proposal to prise him away from Old Trafford.
McTominay is apparently leaning towards staying at the Theatre of Dreams for the 2024-25 campaign, and Man United will not consider selling him unless a significant offer is tabled.
It is unclear if the Red Devils are considering giving McTominay a new contract, but if not, they will run the risk of losing the midfielder on a free transfer in under 12 months' time.
Due to McTominay's status as a home-grown player, any sale this summer would go down as pure profit on Man United's books, although the Red Devils are not in serious danger of breaking Profit and Sustainability Rules.
Since graduating from their youth setup, McTominay has scored 29 goals and provided eight assists in 252 matches for the Red Devils, and he started all three matches for his nation at Euro 2024.
McTominay could stay, but two others might leave
While Ten Hag and McTominay are happy to keep working together, the Red Devils will be receptive to offers for both Casemiro and Christian Eriksen, the latter of whom is also out of contract in 2025.
It had also been suggested that the 20-time English champions would consider selling Mason Mount after his injury-hit first season at Old Trafford, but the ex-Chelsea man is expected to stick around.
Mount was involved in Saturday's 2-0 pre-season win over Rangers, where 18-year-old defender Leny Yoro also made his unofficial debut after his arrival from Lille, and the teenager's performance was widely praised.
Ten Hag's men are now set to jet off to the USA, where they will tackle Arsenal, Real Betis and Liverpool before meeting Manchester City in this year's Community Shield on August 10.