Man United defeated Nottingham at City Ground, thanks to three goals from Weghorst, Marcus Rashford and Bruno Fernandes.
Speaking on Sky Sports, Keane described Weghorst’s goal as huge for Erik ten Hag’s side, while Neville said the striker had put Man United in a really comfortable position.
Keane said: “Great finish, look at his [Weghorst] reactions.
“People have been critical that he has come to the club. That is what he has been brought to the club for. Huge goal for United.”
On his part, Neville said: “There is a little bit to do with the finish and he does really well with the outside of his right foot.
“He’s put Man United in a really comfortable position a quarter of the way through this tie.”