Manchester United reportedly refused to let Diogo Dalot leave the club on transfer deadline day due to them missing out on Kieran Trippier earlier in the window.
Ole Gunnar Solskjaer was keen to bring in reinforcements at right-back to provide more competition for Aaron Wan-Bissaka, and had identified Trippier as his top target in that area of the field.
However, the Red Devils refused to meet Atletico Madrid's asking price for the England international, offering around £18m, whereas the Spanish outfit were holding out for at least £28m.
Man United's interest in Trippier had sparked speculation regarding the future of Dalot, who spent last season on loan at AC Milan and would have been pushed further down the pecking order by Trippier's arrival.
Borussia Dortmund had been in talks with the Portuguese full-back, but Man United would only consider letting him leave if they were able to bring in a replacement.
Spanish outlet Sport1 reports that their failure to sign Trippier therefore caused them to block any deadline day exit for Dalot, who will now spend at least the first half of the season at Old Trafford.
Dalot made 21 Serie A appearances for AC Milan last season, the same number of league outings he has made in total for Man United since joining in 2018.