Since his first ever goal for the Hornets - which came against Bournemouth in an English Premier League tie on October 1, 2017 - the former Nigeria youth international has yet to find the back of the net.
However, the striker got the curtain raiser in the 37th minute to set the visitors on their path to victory over Paul Clement's side.
Success met a low Adam Masina centre before dribbling past goalkeeper Sam Walker to guide into the net.
Wrapping up the win, debutant Domingos Quina scored a 25-yarder as Javi Gracia’s men progressed to the third round of the competition.
Success will, however, hope to get going after his showing at the Madejski Stadium.
So far this season, the former Granada forward has seen action sparingly in Watford's opening three Premier League games and Sunday’s action against Tottenham Hotspur present him another opportunity to convince new manager Gracia.