A memorable five-goal second-half display saw the Hornets inflict a 6-1 drubbing on the Cherries when the two sides met in the league earlier this month.
A repeat never looked likely as the visitors arguably gave a better account of themselves this time around, only to be undone by a bizarre own goal and a counter-attack of real quality.
Gianfranco Zola may have made 10 changes but his side took the lead in unusual fashion after 15 minutes when Fernando Forestieri tried to pick out Javier Acuna from the right but Eliot Ward's interception ended in embarrassment as his attempt to chest the ball back to Ryan Allsop ended with the ball looping over the helpless goalkeeper and into the net.
The lead was almost doubled six minutes later when an audacious cross-field pass from Forestieri set Watford away on the counter-attack and Daniel Pudil nodded the ball on to Davide Faraoni, whose low cross from the right was not too far away from the sliding Acuna.
Bournemouth though, almost levelled with their first effort of note in the 32nd minute when Brett Pitman's low curling effort from a free-kick from the edge of the area was touched onto the post by goalkeeper Jonathan Bond.
Pitman also fired over after a mistake from Faraoni before Acuna went closer at the other end with a deflected 25-yard strike which flew narrowly wide of Allsop's right-hand post.
But the Cherries should have equalised shortly before half-time when Marc Pugh's cross from the left picked out the unmarked Andrew Surman but he headed badly wide of the target.
Watford started the second half at an increased tempo as they sought a potentially decisive second but they needed Bond to come to their rescue again in the 56th minute when he raced from his line to deny Scott MacDonald, who was put through on goal.
Bond also had to hold onto a well-stuck shot from Pugh as Bournemouth continued to threaten to equalise, only to be undone on the counter-attack by a superb Watford second goal in the 65th minute.
Acuna led the charge downfield as he attacked the Cherries defence at pace before slipping the ball forward and to his right where Cristian Battocchio did not break stride as he produced a delightful chip from the edge of the penalty area that beat a bemused Allsop via the underside off his crossbar.
Eddie Howe's side kept battling though, and three minutes later they were almost back in the tie when Ward sent a powerful close-range header goalwards from a corner, only for Bond to pull off the save off the night as he reacted superbly to divert the ball away.
Acuna was not too far away from adding a third with a curling shot as Watford saw out the remainder of the contest with relative comfort.