The Belgium ace is also wanted by Chelsea and there could be a host of other clubs ready to throw their hat into the ring after Lukaku publicly turned down the offer of a new deal at Goodison Park.
Everton boss Ronald Koeman says he remains calm over the situation as the striker has over two years to run on his present deal but, with him turning down the offer of a new contract, the starting gun appears to have been fired on his exit.
United are said to be plotting a move for Lukaku and could use Rooney as bait, Koeman has made no secret of the fact that he would relish the return of the England captain but would like him to play alongside Lukaku not instead of him.
The Old Trafford outfit are refusing to dismiss reports that £60m rated Lukaku is back on Jose Mourinho's summer radar and the United boss also holds an ace up his sleeve in his relationship with Rooney and Lukaku's influential agent, Mino Raiola.
Everton remain confident they will be able to persuade Lukaku to change his mind before his present deal runs out but the clock is now ticking.