While Slaven Bilic's side were disappointingly knocked out of the FA Cup in their quarter-final replay against Manchester United at Upton Park last week, Watford booked a dream trip to Wembley where they face Crystal Palace in the semi-finals this weekend.
With that in mind Quique Sánchez Flores will surely make changes to his side which could well give Bilic the upper hand.
It could also work the other way with Watford's second string players eager to try and earn a place in the side for their big day out at Wembley.
West Ham were once again held to a draw last time out at league leaders Leicester City and in controversial fashion with yet another poor refereeing decision costing them dear.
With European football all to play for, the East Londoners know only a win will do having gone without one for seven games.
So what changes must Bilic make to the side that started against the Foxes when Watford visit the Boleyn Ground for the last ever time?
Collins in for Reid
James Collins has been West Ham's best defender this season and his injury seriously derailed the club's progress in both the FA Cup and league.
In the 11 games he and Angelo Ogbonna have played together this season the Hammers have conceded just eight goals compared to 30 conceded by Winston Reid and Ogbonna in 19 games together.
Reid has looked off the pace since returning from injury and has been at fault for a number of goals recently as well as picking up early bookings which has left him walking a tightrope for the rest of the games.
Lanzini in for Moses
Manuel Lanzini was somewhat surprisingly left out of the West Ham side up at Leicester. He was poor against Manchester United the game before but then so was most of the Hammers side.
Victor Moses actually had a decent game against Claudio Ranieri's men but will probably make way for the tricky little Argentinian who links up with star man Dimitri Payet so well at home.
Sakho in for Obiang
'He scores when he wants' is the chant they sing about Diafra Sakho and Hammers fans will be hoping their killer goal threat returns to the side and some form against Watford.
The Senegal star has been out with injury in recent weeks and will return to the West Ham side after Bilic denied reports of a fall-out with the striker.
While Andy Carroll has hit some goalscoring form, Sakho in full flight very much makes West Ham tick. He should come in for Obiang at home to play up front alongside the big Geordie.
Carroll in for Emenike
Andy Carroll is in red hot form and having only played a half as a substitute at Leicester should be fit to take his place in the side alongside the returning Sakho.
Carroll's aerial prowess coupled with Sakho's pace and power can forge a potent combination.
It's harsh on Emenike who runs his heart out and offers great pace and strength for the cause. One thing Emenike struggles to do, though, is offer a consistent goal threat and for that reason Bilic will understandably revert to Carroll.