London – Manager David Moyes urged West Ham to finish the job after the club effectively sealed its Premier League survival with a first-half blitz in Friday's 3-1 win over Watford.
Moyes' side ran wild before the break thanks to goals from Michail Antonio, Tomas Soucek and Declan Rice.
Troy Deeney got one back for Watford after the interval, but the visitors couldn't pull off an unlikely comeback.
West Ham climbed to 15th place and is now six points clear of the relegation zone with just two games left.
With a vastly superior goal difference to 18th-place Bournemouth and 19th-place Aston Villa, the Hammers should be safe from the drop.
After a second successive win, West Ham needs one point to guarantee its survival.
If other results means the Hammers have to do it themselves, Moyes is confident his players will be up to the task against Manchester United and Aston Villa.
"We are in a good position. Teams still have that chance and we have to do the job," Moyes said.
"Even scoring the goals has helped, I wanted us to keep our goal difference as good as it could be.
"We have 37 points with a couple of games to go. If we get 40 points we'll have done it off our own back."
Watford, in 16th place, is just three points above the relegation zone and faces a nerve-wracking finish to the season.
Nigel Pearson's men, beaten for the first time in three matches, will face Manchester City and Arsenal in their final two games.
Bournemouth, whose goal difference is only two worse than Watford's, would go above the Hornets if it beats Southampton by a three-goal margin on Sunday.
"There's no getting away from the fact this result is bitterly disappointing. I'd expect better from our players," Pearson said. "I'll look at it again and players will get honest feedback. They will go home tonight and think 'wow we've let that one drift past us'.
"It wasn't good enough. We know that we have the toughest run-in but we have to cope with it."
Antonio scored four times in West Ham's rout of Norwich last weekend and the forward was too hot for Watford to handle as well.
West Ham took the lead in the sixth minute when Pablo Fornals played in Antonio, who fired past Ben Foster for his seventh goal since the coronavirus hiatus.
Less than five minutes later, Watford's task was made harder when Soucek headed home from Jarrod Bowen's cross.
England midfielder Rice produced a superb 30-yard strike to put West Ham up by three in the 36th minute.
Deeney reduced the deficit in the 49th minute, tapping in after Abdoulaye Doucoure's shot rebounded off a post.
But Deeney was forced off with an injury and Watford couldn't fight back without their captain.