Liverpool’s opener came when West Ham was least expecting it. The home side was looking to score as it took a corner but the ball was in the net at the other end just 13 seconds later.
Salah flicked a clearance into Mane’s path, releasing the Senegal winger into space before he returned the ball to Salah on the edge of the penalty area to finish calmly past goalkeeper Joe Hart.
Less than three minutes later the lead was doubled. Matip tapped into an empty net after Hart initially prevented an own goal with a fine save.
West Ham got back into the game 10 minutes after the break. Ayew this time crossed to Lanzini at the back post, and Lanzini controlled the ball expertly on his chest before poking a smart finish past Simon Mignolet.
However, hope for West Ham lasted just 55 seconds.
Liverpool’s two-goal lead was restored as Oxlade-Chamberlain squeezed a shot past Hart, after the keeper kept out his initial effort.
Salah completed the rout 15 minutes from the end, receiving the ball from Mane before driving a powerful effort across goal into the bottom corner.
After an embarrassing 3-0 loss to Brighton in its last home league game, West Ham’s display did little to relieve the increasing pressure on manager Slaven Bilic.
“I definitely don’t feel a broken man. I’m very, very strong,” Bilic said. “On the other hand, the situation for West Ham is not good.”
The Hammers dropped to 17th, with just a point separating them from the relegation zone.
