"I think (United will improve as he improves)", Mourinho said of Pogba after Saturday's 1-0 win.
United have been tight defensively this season, however, with just six goals conceded in 13 matches proving the best record in the division. With Pogba, United tend to be more assertive and against a Watford side who could be got at, it's imperative that the visitors go with the right attitude from minute one to avoid a repeat of last season.
All 10 of their dropped points this season have come on the road with draws at Stoke and Liverpool followed by defeats at Huddersfield and Chelsea, in their last trip away from Old Trafford.
Following victories versus West Ham and Newcastle in the last two matchdays, the Hornets will be looking to win three successive Premier League games for the first time since December 2015 (four in a row).
Watford take on Manchester United at Vicarage Road on Tuesday night (8pm) with both teams in fine form.
Watford are coming off an impressive 3-0 win against Newcastle What are the odds?
Sebastian Prodl is pushing to be involved after appearing as a late substitute against the Magpies, but Andre Gray is expected to keep his position at centre-forward despite the return of captain Troy Deeney from suspension.
Richarlison has been on fire for Watford with five goals and three assistsWhat is the team news? There could be a hope Eric Bailly is available soon with Phil Jones also on the road to recovery after aggravating an injury on global duty with England. Marcos Rojo is also in line to start as Mourinho considers selecting a three-man central defence.
It had been claimed that Lukaku could be banned for a kick out at Brighton's Gaetan Bong at the weekend, but the striker will face no action from the FA.
And the Hornets boss has revealed the clash will have an extra edge due to his friendship with United boss Mourinho.