On a Saturday when Ange Postecoglou enjoyed further release of pressure with Spurs' 4-1 win at Ipswich and Manchester United again struggled in their comeback 2-2 draw at Everton, second-placed Arsenal squandered a great chance to trim the gap to Liverpool to five points.
Jarrod Bowen's first-half header secured an unlikely win for West Ham, who arrived at Emirates Stadium with just one victory in their last eight games.
There was worse to come for Arsenal, with left back Myles Lewis-Skelly handed a red card following a video review for his foul as the last man.
The team's disciplinary record under Arteta has come under scrutiny this season — and might yet cost the Gunners the title, along with key injuries to their attack.
With the likes of Kai Havertz, Bukayo Saka, Gabriel Martinelli and Gabriel Jesus out injured, Arsenal had only two shots on target.
It leaves Liverpool still with an eight-point cushion, having played the same number of games as Arsenal, and that advantage could grow when the leaders play Manchester City away on Sunday.
At Goodison, Man United came from two goals down before benefiting from a last-gasp video-review call to earn their draw.
Uruguay midfielder Manuel Ugarte grabbed the 80th-minute equaliser for United with his first goal at club level in four years, eight minutes after Bruno Fernandes started the visitors' fightback at Goodison Park by curling in a free kick.
United had been on course to slip to a third straight loss — and ninth defeat in 15 league matches since Ruben Amorim took charge in November — after first-half goals by Beto and Abdoulaye Doucoure for resurgent Everton.
There was a late scare for United when Everton were awarded a penalty for what appeared to be a foul by Harry Maguire on Ashley Young, who fell to the ground dramatically under pressure from Maguire and Matthijs de Ligt in the third minute of stoppage time.
Following a video review, on-field referee Andrew Madley was advised to view the incident again on the pitchside monitor and he changed his initial decision.
"I think it was a soft penalty, it was clear," Amorim said.
At Portman Road, a first-half brace by Brennan Johnson at his father's old stomping ground inspired Tottenham to their easy win over Ipswich.
David Johnson had been prolific at Portman Road across a four-year spell and his lad Brennan followed in his footsteps with two quickfire goals in Suffolk to set Postecoglou's side on course for a third straight Premier League win.
Omari Hutchinson pulled one back for Kieran McKenna's side before half-time and relegation-threatened Ipswich did have other chances, but Tottenham made the points safe with late strikes by Djed Spence and Dejan Kulusevski.
It continued Spurs' mini-revival, winning three league fixtures on the bounce for the first time since December 2023 as they aim to put a difficult winter behind them.
Elsewhere, fifth-place Bournemouth lost momentum in a 1-0 home defeat to Wolves which damaged their bid to finish in the Champions League qualification positions.
Bournemouth defender Illya Zabarnyi's 31st-minute red card was quickly followed by the winning goal by Matheus Cunha for Wolves.
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