The Serie A champions have resigned themselves to losing Lukaku, former United, Everton and West Brom hitman, after his former club offered to meet Inter’s asking price to bring him back to Stamford Bridge.
Lukaku’s exit could then open the door for Martial to leave Old Trafford.
Inter want to loan the 25-year-old for the season despite their huge windfall – and United will agree if the Italian club accept their demand that a purchase obligation must be included in any deal.
United want to recoup most of the £ 50million they paid Monaco to sign Martial six years ago.
Everton have also been linked with a loan for the United striker.
Inter failed in a previous attempt to sign Martial in 2019.
He still has three years left on his £ 200,000-a-week contract at Manchester, but Inter are prepared to cover that cost.
Martial, who has been sidelined with a knee ligament injury since March, has fallen behind Edinson Cavani, Mason Greenwood, Marcus Rashford and new signing Jadon Sancho in Ole Gunnar Solskjaer’s plans.
Rashford chose to undergo surgery to cure the shoulder problem that plagued him for most of last season and could be missing for three months.
But Martial only scored four times in the Premier League last season and United are ready to let him go if the right deal can be made.
Ole Gunnar Solskjaer discussed the introduction of new signings Jadon Sancho and Raphael Varane after Sunday’s 4-0 friendly victory over Everton.
“Of course, the medical examination with Raphael has to be done,” Solksjaer told MUTV.
“He’s isolating right now, he had to wait for the visas so unfortunately it took a few more days than expected but we’re going to follow the protocols and the rules so it took a few more days than we expected.
“Jadon is here for Monday and I hope he will be in a decent nickname then and can be involved.”
“I hope we have Raphael and Jadon with the group,” Solskjaer added, speaking to MUTV.
“It’s important for us when you sign two players like that, that you integrate them. “
United will face Leeds United in their opening game of the new Premier League season next weekend.