Trent Alexander-Arnold equalised with a brilliant free-kick, but Alisson was at fault again as Pablo Fornals and Kurt Zouma struck for the Hammers after halftime.

Divock Origi got one back for Liverpool, but it wasn't enough to preserve their long unbeaten streak.

Klopp was furious with West Ham's first goal, saying Alisson was fouled by Angelo Ogbonna and that Craig Pawson should have sent off Aaron Cresswell for a nasty foul on Jordan Henderson.

"The first they score is a foul on the goalkeeper. The arm goes into Alisson's arm so how can he catch it? That makes no sense," Klopp said.

"What can Alisson do? People will say I'm making excuses but I'm calm. 

"You need normal decisions from a referee and he did not do that. Cresswell's was a reckless challenge on Henderson. It was a clear red card."

Liverpool dropped to fourth place in the Premier League as West Ham climbed into third.

The Reds are four points behind leaders Chelsea, while West Ham are only three adrift of Thomas Tuchel's men.

"However long a run is, it will come to an end. It looked like we lost a bit of patience. We were not that calm in the decisive moments. We can be better 100 per cent," Klopp said.

West Ham's first league win against Liverpool since 2016 was also their manager David Moyes' maiden league success against Klopp at the eighth attempt.

Moyes has worked wonders in his second spell at West Ham and a challenge for a Champions League place will be in their sights if they can maintain this level of performance.

"It's been hard to beat Liverpool over my career, so I was very pleased to get it. It was a terrific effort," Moyes said.

"I'm hugely proud. The way the players have gone about it, you talk about me turning it around, these players were close to relegation. Now we're pushing for Europe."

REDS ROCKED

In the fourth minute, Fornals' inswinging corner raced towards Ogbonna, who got in front of Alisson with a jump that obstructed the Brazilian's view.

Ogbonna's arm made contact with Alisson as the keeper's flailing attempt to punch clear diverted the ball behind him and into his own net.

A lengthy VAR check followed as Liverpool's players surrounded Pawson to claim both a foul on Alisson and a handball by Ogbonna, but the goal was allowed to stand.

Alexander-Arnold brought Liverpool level in stunning style in the 41st minute.

Mohamed Salah's quick feet drew a foul from Declan Rice on the edge of the area and Alexander-Arnold curled a brilliant strike over the wall and into the top corner of Lukasz Fabianski's net.

Liverpool's commitment to throwing bodies forward in search of the win came back to bite them in the 67th minute.

After Sadio Mane lost possession, Jarrod Bowen embarked on a mesmerising run before slipping a pass to Fornals, whose low shot from the edge of the area slipped under Alisson's weak attempted save.

Alisson's nightmare wasn't finished. The keeper was caught out of position as Zouma headed West Ham's third goal from Bowen's 74th-minute corner.

Origi scuffed home in the 83rd minute to give Liverpool hope.

But Mane headed inches wide of the far post as West Ham survived a tense finale. (Reuters)