Jose Mourinho is desperate to splash the cash with Champions League football returning to Old Trafford next season.
The United boss has already landed Everton talisman Romelu Lukaku, Chelsea's Nemanja Matic and Victor Lindelof from Benfica.
Mourinho has been vocal about his transfer plans, claiming he wanted four signings this summer to build a Premier League title charge next season.
However, Sky Sports claim the Red Devils could be forced to sell players before spending again in the transfer market.
They add that United are not pursuing other targets, despite being heavily linked with Inter Milan winger Ivan Perisic and Paris St-Germain right-back Serge Aurier.
Red Devils aces David De Gea, Matteo Darmian, Chris Smalling and Marouane Fellaini have all been linked with an Old Trafford exit this summer.
Speaking about his transfer plans, Mourinho said last month: "I'm happy with my squad, but I would like to have two more players, I never hide that.
"One player - a midfield player - would give me more options to the balance and the team, another one an attacking player, especially that can play through the wings to give me more attacking options.
"But I never speak about players that belong to other teams, I don't like it if any manager comes and would say he would like one of my players, that's not correct."
