Lukaku was in danger of missing tonight’s match after kicking out Brighton defender Gaetan Bong.
But the Belgian starts in the Manchester United attack with Jose Mourinho switching to a 3-4-2-1 formation.
Marcos Rojo makes his first start of the season after a knee injury and Jesse Lingard comes in for Marcus Rashford.
For Watford, Marco Silva makes one change with Sebastian Prodl replacing the injured Miguel Britos in defence.
Watford: Gomes, Zeegelaar, Mariappa, Kabasele, Prodl, Femenia, Hughes, Cleverley, Doucoure, Richarlison, Gray.
Subs: Karnezis, Janmaat, Deeney, Wague, Carrillo, Capoue, Pereyra
Man Utd: De Gea, Valencia, Rojo, Smalling, Lindelof, Young, Matic, Pogba, Lingard, Martial, Lukaku.
Subs: Romero, Mata, Ibrahimovic, Rashford, Herrera, Darmian, McTominay