The 18-year-old has not played for the senior team since suffering a serious ankle injury picked up in a freak collision just two minutes into the pre-season friendly with Real Madrid. He was selected to start ahead of a number of senior players for the fixture, and Erik ten Hag had seemed to signal his intentions.
Mainoo made his senior debut in Januarys League Cup quarter-final clash with Charlton Athletic before being afforded two more appearances in the weeks after. He may have had more if he had not picked up a knock towards the end of the campaign.
The teenager – who subsequently signed a new deal in February – has been recently getting back up to speed with the academy. He grabbed a couple of assists against League Two Salford City in the EFL Trophy a fortnight ago and looked head-and-shoulders above the rest.
United have been careful to manage his recovery but Mainoo is now back in matchday squads. He has made the last three Premier League squads and surely a return to action is close.
The door has been left ajar by injuries in midfield. Casemiro, of course, is a slightly different type of central player but his absence until the new year means a spot in midfield is nevertheless up for grabs.
More recently, Christian Eriksen has been added to the physio chart. The Dane suffered a knee injury in Saturdays win over Luton Town and had to be withdrawn before half-time. It leaves the midfield ranks thinned for at least a month.
Mason Mount has failed to get going so far while Hannibal Mejbri is a prospect but, right now, a liability with three yellow cards in just five matches. Scott McTominay has been in good form while Sofyan Amrabat has shown he has something to offer.
But amidst it all, there must surely be space for Mainoo to make his return. Ten Hag promised the youngster he would get minutes when the nights started drawing in, once he was fully recovered.
Back in August, Ten Hag suggested Mainoo had the ability to complement a midfield pivot and gave an update on the youngster. He said: “I know, in this moment, he&aposs not there, but Kobbie Mainoo, we have seen him against Arsenal [in pre-season], he is ready to pick that role.