Barcelona played Frenkie de Jong out of position after leaving him out of their starting line-up for their opening pre-season friendly on Tuesday as his transfer saga continues.
United have spent all summer trying to get a deal over the line for the Dutch midfielder.
They finally reached a £71.5million agreement with Barcelona but issues surrounding a sum of £17m in deferred wages and bonuses owed to the midfielder has stalled any move.
De Jong appeared to show his frustration over the weekend as he was caught liking an Instagram post which said 'I dislike the way we have handled Frenkie's situation'.