Marcos Rojo suffered another injury setback on Friday night as he hobbled off during his comeback game for Manchester United's Under-23 side.
The defender had not played since suffering an injury during Argentina's World Cup round-of-16 defeat to France earlier this summer.
And despite efforts to step up his fitness ahead of a potential first-team return, Rojo had to be replaced by Regan Poole before the hour mark at Old Trafford.
A frustrated Rojo headed straight down the tunnel with a team medic after failing to complete 90 minutes for Ricky Sbragia's side in the Premier League 2 clash.
Despite Rojo's anger, there was at least some positive news on the injury front as summer signing Diogo Dalot made his second appearance for the reserve team at right back.
The 19-year-old also played against Stoke two weeks ago as he looks to step up his recovery from a knee problem.
Mourinho and his United squad were spotted at Stockport train station on Friday as they headed south on the eve of their Premier League clash with Watford.
The Portuguese boss eased the pressure on himself with a 2-0 victory over Burnley before the international break and he will be desperate to pick up all three points against the Hornets, who have made a perfect start to the new season.
And ahead of Saturday's clash at Vicarage Road, the likes of Romelu Lukaku, Alexis Sanchez, Marcus Rashford and Fred were pictured arriving at United's Carrington base for a training session before going to Stockport.