Monaco midfielder Fabinho appeared to storm out of training on Monday as he seeks a summer move away from the club.
The Brazilian has already seen some of his team-mates quit France for the Premier League and is keen to follow suit as the clock counts down to the end of the transfer window.
Fabinho played the full 90 minutes as Monaco began the defence of their Ligue 1 title with a 3-2 win over Toulouse on Friday night, but a video has appeared of the 23-year-old throwing his bib to the ground and walking off after an alleged bust-up with team-mate Kylian Mbappe on Monday.
Despite the French media not making a big deal of the issue, the video has gone viral and rumours persist that the player is trying to force his way out of the club.
Although United no longer have an immediate need for a holding midfielder, following the arrival of Nemanja Matic, the fact that Fabinho can also fill in at the back is a huge plus point for Red Devils boss Jose Mourinho.
PSG have also shown an interest in the versatile star but Monaco are not keen on selling to a direct rival so United remain in pole position for the player, should Monaco decide to sell.