LONDON -- The debate over whether Arsenal can handle a Premier League title run-in just grew louder.

After falling short last season despite holding an eight-point lead at the beginning of April, the principal challenge this time around for manager Mikel Arteta was evolving the Gunners into a more robust proposition to last the pace.

There had been clear signs of progress in that regard this season, but the manner of Thursday's 2-0 defeat to West Ham will spark familiar questions about whether Arsenal can triumph in what is threatening to be a multiway fight to be champions.

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A row will continue over the opening goal given the ball may have drifted out of play as Jarrod Bowen pulled it back for Tomás Soucek to score after 13 minutes. VAR official Craig Pawson took a long look but no camera angle could conclusively overturn the on-field decision and a goal was awarded.

Regardless, Arsenal lacked the composure associated with serial title-winners. Their defending -- which led to Gabriel Magalhaes hitting the ball against Oleksandr Zinchenko to give Bowen a chance to pounce -- was calamitous on the first goal. Their response in possession was even more troubling. Wasting chances at one end and conceding another soft goal at the other was a recipe for disaster.

The pre-match talk of a summer signing coming back to haunt his former club came to pass but not in the manner anyone expected. This ended up being a night to forget for Declan Rice as ex-Arsenal defender Konstantinos Mavropanos scored his first Premier League goal with an excellent 55th-minute header.

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After excelling for his new club time and again this season, Rice endured the taunts of West Ham fans for the final 20 minutes or so here as a result of his £105 million summer move to Emirates Stadium. Rice's form has been a big factor in Arsenal's apparent evolution but, in a moment that perfectly encapsulated their regression here, he gave away a penalty in stoppage time, bringing arguably the biggest cheer of the night from the away end. Few seemed to care that David Raya saved substitute Saïd Benrahma's spot kick as the final whistle came seconds later.

Arteta has rightly praised the home atmosphere in recent times, given the transformation from the toxic disconnect that provided the soundtrack to the end of Arsene Wenger's time in charge -- but there was a tension in the air against the Hammers that did not dissipate all evening.

There wasn't the maturity in Arsenal's play that we have come to expect, perhaps most obviously evidenced by their play in the final third. Gabriel Jesus headed the ball over on 66 minutes and Martin Odegaard forced Alphonse Areola into a fine save at the end, but there was little else of note despite registering 77 touches in West Ham's box -- the most on record since 2008-09 in a single Premier League match for a team who failed to score.

Bukayo Saka (who hit the post in the first half), Emile Smith Rowe and Eddie Nketiah all registered shots on target in the final 12 minutes but none of them required anything other than a simple stop by Areola. Arteta, however, believed they created enough to win the game.

"When you look at how much we generated in the game, to see the result is very disappointing," Arteta said. "But they were better than us in both boxes. They had two shots, with the penalty three. We had 30, I don't know how many touches in the box, how many situations, how many opportunities to score and we haven't done it. In football you have to do that better if you want to win.

"It's what it is. We have to try to generate. If we don't score with 30 shots, then we have to do 50 or 60 to try to score. That's the only thing. I can't imagine a game where we have more touches in the box, more dominance and less situations for the opponent against a really good West Ham side. Today though, it wasn't enough to win the game."

After West Ham United scored a second goal, Arsenal players -- including Martin Odegaard, center -- were visibly shell-shocked. Shaun Botterill/Getty Images

Their failure in front of goal will also only strengthen the argument a new striker is needed in January.

"All we have is the players we have, the players I love the most," said Arteta. "What we have to do is try to get better situations, more training, raise the confidence and that's it. They've done it [before]."

West Ham and manager David Moyes continue to defy expectations. After winning last season's Europa Conference League and selling Rice for a club-record fee, they now find themselves in sixth place on 33 points, the highest figure they have ever collected at this stage of a Premier League season. No wonder Moyes suggested the club is "getting ready to talk" about a new contract with his existing deal expiring at the end of the season.

Thursday was West Ham's first win in this fixture since 2015 and, more remarkably, Moyes' first league away win at Arsenal, Chelsea, Liverpool or Manchester United in 73 attempts.

"Football is played in many ways and tonight we did the part that maybe isn't talked about as much," said Moyes. "Brilliant defending. We did a good job on Arsenal tonight. They had lots of the ball, too much for my liking, but we did a great job."

Asked about his team's aspirations for 2024, Moyes added: "We are not one of the top teams. We are trying to get up and grow the team."

Arsenal, meanwhile, are in a different place. They believe they can be the top team. But this defeat showed there is more work to do.