The England centre-back has spent the season on loan with the Serie A club, with his deal recently extended to cover the final game of the domestic term last weekend.

However, the latest arrangement agreed between United and Roma did not cover the UEFA Europa League, a competition in which Smalling's parent club remains involved.

"I'm gutted that I can't finish what we started this season," Smalling wrote on Twitter alongside four pictures of him in a Roma shirt.

"To experience the love shown to me in such a short time was extra special and it will not be forgotten.

"I want to thank and wish all the players and staff the best of luck against Sevilla. DAJE ROMA!"

Smalling, 30, played in 30 of Roma's Serie A matches as it finished fifth, while he also made five starts in the UEFA Europa League.

Although Smalling will now return to Old Trafford, he is ineligible for the remainder of United's UEFA Europa League campaign.

It may be a different story for Alexis Sanchez – another United loan export who has spent the 2019-2020 season in Serie A with Inter Milan.

Inter has included the Chile forward in its squad for the latter stages of the UEFA Europa League ahead of its Round of 16 tie with Getafe this week.

For Sanchez to have any involvement beyond that, Inter and United would need to reach an agreement on a longer-term deal.