West Brom started in the worst way possible when Ajayi's stray back pass put Antonio in one-on-one in the opening seconds of the match. Goalkeeper Johnstone took down the Hammers striker in the box, only for Declan Rice to hit the post from the resultant spot kick.
West Brom were let off the hook, and they used this momentum along with the encouragement from the fans to their advantage. Pereira whipped in an audacious corner directly at goal after 27 minutes, the ball flying past late stand in Randolph via a flick off of Thomas Soucek.
The Czech international eventually atoned for this diversion, however, pulling United back into the game on the stroke of half time by converting Benrahma's cross into an empty net. VAR had a long look for a fractional offside, but the goal stood - game on for the second half.
The second half featured chances for both teams, West Brom failing to convert a goalmouth scramble along with Cresswell's audacious free kick hitting the post. West Ham had to wait a while to put themselves in front, but they did so with just eight minutes to spare. It was the away side's turn to score from the corner, this time through Ogbonna's close range header at the back post.
As West Brom looked for an equaliser, they left themselves exposed at the back, leaving space for West Ham to break. They did so late on with Lingard, who played in Antonio who then finished with aplom, making it 1-3 after 88 minutes and killing the game off as a contest.
With the victory and following Spurs' defeat at home to Villa earlier in the day, West Ham climb up to sixth in the table. Avoiding defeat in their final game at home to Southampton will secure them a Europa League finish, an incredible feat for David Moyes' team.