LONDON (Reuters) -Arsenal moved into the Premier League's top four at West Ham United's expense as goals by Gabriel Martinelli and Emile Smith Rowe earned a 2-0 win in a lively London derby on Wednesday.
Brazilian forward Martinelli struck just after halftime with a clinical finish and substitute fellow youngster Smith Rowe eventually gave a dominant Arsenal some welcome breathing space with a superb 87th-minute effort.
It could have been a more comfortable night for Arsenal had Alexandre Lacazette, captain again in place of the disciplined Pierre-Emerick Aubameyang, not had his penalty saved midway through the second half.
West Ham, for whom Vladimir Coufal was red-carded after conceding the penalty, failed to produce the kind of form that has seen them stationed in the top four since October.
They huffed and puffed and threatened sporadically but home keeper Aaron Ramsdale's only real save was from a Jarrod Bowen effort shortly after Martinelli's opener.
Victory hoisted Arsenal up two places into fourth spot with 29 points from 17 games with West Ham on 28.
The pre-match build-up had been dominated by Arsenal's decision to strip Aubameyang of the captaincy for another lapse of discipline. But just as in the comfortable win against Southampton at the weekend, Arsenal did not miss him.
Mikel Arteta's side responded with a vibrant second-half display after a rather scrappy opening half hour, with French forward Lacazette, who also wore the armband against Southampton, leading by example.
"Really pleased with the attitude, the commitment, the quality that we showed in the game," Arteta told reporters.
"The players play for the club and the pride that we expect from them. I was really happy from the beginning, because we knew that we had to play really good today to beat West Ham."
On Lacazette's leadership, Arteta added: "He's next in line. It's in his nature. He's not a selfish player. He's a player that's happy when he makes the team better."
Disappointing as they were, West Ham's players were furious at Anthony Taylor's decision to show Coufal a second yellow card. Replays showed he had made contact with the ball before sending Lacazette tumbling for the penalty, although Moyes was in no mood to make excuses.
"I didn't think a lot of our performance generally, Arsenal played well with good intensity and we couldn't deal with it," Moyes said. "(Coufal) got the ball but he should have got more of the ball."
A frantic opening half saw West Ham's Craig Dawson slice the first chance of the night high and wide while Pablo Fornals curled a right-footed effort wide for the visitors.
But as halftime approached Arsenal were dominating and were close to taking the lead when Kieran Tierney's fiercely-struck shot was touched on to the crossbar by keeper Lukasz Fabianski.
Fabianski was then alert to keep out Lacazette's shot before Dawson produced a goal-saving tackle to stop Martinelli pouncing on the rebound.
It did not take Arsenal long to take the lead in the second half as Lacazette was given too much space and time to slide a pass through to Martinelli who calmly shot past Fabianski.
Lacazette was a constant menace and went down under a challenge from Coufal and the referee pointed to the spot, before showing the Czech defender a second yellow card.
Fabianski saved Lacazette's spot kick and as further chances went begging it seemed Arsenal might pay for their failure to finish off the lacklustre visitors.
But Smith Rowe came off the bench and soon raced on to a pass by the impressive Bukayo Sako before curling home left-footed to make the points safe.
(Reporting by Martyn HermanEditing by Toby Davis)