Marcus Rashford starts a three-match suspension this weekend after a straight red card against Burnley before the international break.
Luke Shaw suffered concussion in England's UEFA Nations League defeat to Spain last weekend but is available for United here. However, he hasn't trained all week.
Marouane Fellaini was not risked by Belgium during the international break but is expected to retain his spot in midfield for United to counter Troy Deeney's physicality in attack.
Diogo Dalot and Marcos Rojo will play for the U23s on Friday night to complete their recovery process. They will be considered for first-team games after that.
Ander Herrera, Phil Jones and Sergio Romero are other fitness concerns for Jose Mourinho on Saturday.
Watford are one of only three sides with a 100 per cent record in the Premier League this season. The Hornets have incredibly won their opening four matches.
Manchester United have won two and lost two of their opening four and languish down in mid-table. It's been a difficult start to the season for Jose Mourinho and it shows no sign of relenting here.
United have struggled at Vicrage Road of late. They have conceded on each of their last five visits and have shipped five goals in their last two. Did the international break come at the wrong time for Watford or can they inflict more misery on Mourinho's side?
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