Cristian Battachio had put the Hornets into a first-half lead but late goals from Thomas Ince and Gary MacKenzie gave the visitors a valuable victory in their survival battle.
Glenn Murray continued his prolific season for Crystal Palace as his brace helped them climb above Hull into third place, but they were denied all three points as Wales international Steve Morison grabbed a double of his own for Leeds in a 2-2 draw.
Nottingham Forest climbed into the play-off places and increased Wolves' relegation fears with a 3-1 victory at the City Ground.
Henri Lansbury put the hosts ahead before Matt Doherty levelled, but Lansbury's second and Lewis McGugan's late strike, which came after Stephen Ward was sent off, sealed the win.
Sheffield Wednesday picked up an important win and dented Leicester's play-off hopes as Connor Wickham got the only goal for the Owls, while Marcos Alonso gave Bolton a 1-0 win over Brighton, who had Ashley Barnes dismissed in the dying minutes.
Bristol City increased their hopes of escaping relegation with a 2-0 home win over Middlesbrough. Albert Adomah and Steven Davies got the goals for Sean O'Driscoll's side.
Peterborough played out a goalless draw with Ipswich, while Callum Harriott's early goal gave Charlton a 1-0 win at Huddersfield.
The day's other game saw Birmingham come from a goal down to claim a 3-1 home win over Derby.
Ben Davies put the Rams ahead but a Wes Thomas brace and a strike from Nathan Redmond gave the Blues victory.
- Sports & Recreation
- Henri Lansbury