will not feature in a behind-closed-doors friendly at Carrington this week as had originally been planned.
The midfielder has been out of action for over two months since injuring his ankle on United’s tour.
Mainoo was the early star of the tour, featuring in three matches before he started against in a fourth appearance.
The 18-year-old was named Man of the Match in a win against , and he was widely praised by Erik ten Hag.
However, he returned to training last week and trained alongside the first team before the Champions League defeat to Galatasaray.
United planned a behind-closed-doors friendly against Barnsley on Tuesday, with Ten Hag hopeful that Mainoo could feature alongside Sergio Reguillon and Raphael Varane.
However, the Daily Mail say the game has come to soon for Mainoo and his return date has therefore been pushed back.
The likes of Luke Shaw and Lisandro Martinez remain long-term absentees, while Tyrell Malacia is still up to three weeks’ away.
United take on Sheffield United at Bramall Lane when they return from the international break.
Ten Hag hopes to have Reguillon back, with the Spaniard missing the last three weeks.
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