The Hornets held their profligate counterparts the Red Devils to a 0-0 draw in the PL week 24 encounter.
Nigeria’s Dennis hardly got on the ball and attempted just one shot and failed to create a single chance in what was his 20th game of the season for Watford.
Manchester United dominated the encounter and created an incredible 20 chances but couldn’t find a way behind a Watford defense without Super Eagles centre back, William Troost-Ekong.
Super stars like Cristiano Ronaldo, Bruno Fernandes, Paul Pogba and much-praised youngster, Anthony Elanga were all guilty of missing very good opportunities to win the game for the home side.
United subbed on Jadon Sancho and Marcus Rashford but a goal remained elusive at Old Trafford, with Watford holding on for a share of the spoils.
With the result, United remain fourth on the table with 45 points, just two ahead of fifth placed Arsenal despite the Red Devils having played three matches more.
Ralf Rangnick men miss a good chance to take three points before going into a difficult run of games that will see them face Manchester City, who they play next, Tottenham, Atletico Madrid and Liverpool in that order.