Potter has won just five of 21 games since taking charge in January and has endured a miserable start to the new campaign after a 3-0 defeat to newly-promoted Sunderland last weekend.

Lucas Paqueta's brilliant strike gave the home side hope early on, but they quickly capitulated.

"It was a tough evening for us," said Potter. "Against a top team, to concede the goals in the manner we have, it is an impossible task."

Joao Pedro scored the first of Chelsea's three goals from corners before Pedro Neto and Enzo Fernandez added to the world champions' lead.

Moises Caicedo and Trevoh Chalobah then took advantage of a nightmare night for new West Ham goalkeeper Mads Hermansen.

Victory took Chelsea, who drew their opening game 0-0 against Crystal Palace, top of the Premier League for the first time since December 2021.

Chelsea had been dealt a blow before kick-off as Cole Palmer left the field during the warm-up and was pulled out of Enzo Maresca's line-up as a precaution due to a muscle injury.

"The last four or five days he was not 100 percent. We prefer not to take any risks and we see in the next hours (how serious the injury is)," said Maresca.

Palmer's withdrawal opened the door for Brazilian wonder kid Estevao to show his potential on his first Premier League start.

However, it was another Brazilian who opened the scoring in spectacular fashion.

Paqueta had faced an uncertain future for two years until he was cleared of spot-fixing allegations by an independent regulatory commission last month.

The 27-year-old had thanked the club for standing by him as the English Football Association reportedly sought a lifetime ban.

After blasting into the top corner from long range, Paqueta pointed to the badge on his chest repeatedly during an emotional celebration.

West Ham's joy, though, lasted just nine minutes before Chelsea turned the tide.

Pedro made himself an instant hero for the Blues by scoring three goals in as many games as Chelsea won the Club World Cup less than six weeks ago.

The former Brighton forward had a simple task for his first Premier League goal for the club as he headed in Marc Cucurella's flick-on from a corner.

West Ham briefly thought they had retaken the lead through Niclas Fuellkrug until the goal was disallowed for offside after a VAR review.

Moments later, the hosts trailed when Pedro picked out Neto to finish at the far post.

- Hermansen howlers -

Estevao scored against Chelsea in his final game for Palmeiras at the Club World Cup and has been hailed as one of the brightest young talents in world football.

The 18-year-old showed his explosive pace to burst clear of the sluggish West Ham defence and square for Fernandez to make it 3-1 on 34 minutes.

West Ham have been among the quietest Premier League clubs during a record spending spree in the summer transfer window.

But one of the few new arrivals is off to an inauspicious start as goalkeeper Hermansen was then at fault for Chelsea's fourth and fifth.

The £20 million ($27 million) signing from Leicester dropped a corner at the feet of Caicedo, who prodded into an empty net.

Hermansen got nowhere near the Blues' next corner and the ball broke kindly for Chalobah to rub salt into West Ham wounds.

Thousands of home fans fled for the exits with over 30 minutes remaining, but those who remained lustily booed at the full-time whistle.

Potter, who was sacked after just seven months in charge of Chelsea in 2023, must hope for more understanding from his superiors to turn around a dreadful start.