West Ham climbed out of the relegation zone with a first league win since 1 January, while Chelsea’s hopes of finishing in the top four were dented after being held at Bournemouth.
Jarrod Bowen scored on his first Premier League start as the Hammers swept aside Southampton 3-1 at London Stadium.
Signed from Championship club Hull City in a £20m-plus deal in January, Bowen gave David Moyes’ strugglers the perfect start before Michael Obafemi’s equaliser.
But West Ham climbed above Aston Villa, who play Manchester City in the Carabao Cup final on Sunday, and Bournemouth into 16th spot after goals by Sebastian Haller and Michail Antonio.
Villa, who have a game in hand, are two points from safety.
It was all going to plan for fourth-placed Chelsea when Marcos Alonso, who netted the winner against Tottenham last week, put his side ahead at lowly Bournemouth.
However, the Cherries hit back with two goals in the space of three minutes to take the lead.
Colombia midfielder Jefferson Lerma made it 1-1 before Joshua King’s first Premier League goal since 2 November looked to have earned Eddie Howe’s side a third successive Premier League home win.
In a thrilling game, Alonso’s third goal in two league games salvaged a point for Chelsea, who remain fourth – four points above fifth-placed Manchester United who play at Everton on Sunday (14:00 GMT).
Jordan Ayew’s goal ensured Brighton’s dismal start to 2020 continued as Crystal Palace secured a narrow 1-0 win at Amex Stadium.
The Ghana forward fired low under Mat Ryan after being set up by Christian Benteke.
The result leaves Palace nestled safely in mid-table, while the Seagulls sit three points above the bottom three and without a league win since 28 December with home matches against Arsenal, Manchester United, Liverpool and Manchester City on the horizon.
There were more yellow cards (7) than shots on target (5) as Burnley’s visit to Newcastle ended in a goalless stalemate.
The Clarets, ninth in the table, are unbeaten in their last six league games while they have secured clean sheets in four of the last five.
Runaway leaders Liverpool will open up a 25-point lead at the top of the table if they win at next-to-bottom Watford in Saturday’s late kick-off (17:30 GMT).
