Rafael Benitez sprung a suprise with his team selection as he opted for a 3-4-3 system with Crouch, Bellamy and Dirk Kuyt all starting. The system worked as Liverpool controlled the game from start to finish.
Liverpool thought they'd taken the lead in the twelfth minute when Daniel Agger slotted home following a corner but his goal was correctly ruled out for offside.
That was a temporary respite for Watford however. Liverpool took the lead on 34 minutes when Hornets goalkeeper Ben Foster palmed the ball out to Steve Finnan who cleverly played it across the box to Bellamy who slotted home from six yards out.
Liverpool doubled their lead five minutes before half time when Dirk Kuyt's header released Bellamy. The Wales striker's shot was excellently saved but Peter Crouch was on hand to head home the rebound.
The game was all over three minutes into the second half when Crouch scored his second of the game and twelfth of the season. Fabio Aurelio sent Bellamy clear down the left and his cross was steered home from twelve yards.
The Reds had chances for a fourth but once the game was won they did ease off, with next week's game against second placed Chelsea in mind. Liverpool can go into that match full of confidence after a comfortable win yesterday.