However, substitute Emile Smith Rowe added Arsenal’s second just before full-time to secure the three points for Mikel Arteta’s side and leapfrog West Ham into the Champions League places.
“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.”
The pre-match build-up had been dominated by Arsenal’s decision to strip Pierre-Emerick Aubameyang of the captaincy for another lapse of discipline. Just as in the comfortable win against Southampton at the weekend, Arsenal did not miss him.
A testy first half ended with no goals and West Ham’s Vladimír Coufal seeing yellow early on for an elbow to the face of Arsenal’s Kieran Tierney.
Arsenal forced the issue toward the end of the opening 45 minutes with some nice interplay in the offensive third and West Ham keeper Lukasz Fabianski needing to make a few crucial saves to keep it 0-0 at half-time.
Martinelli’s goal came soon after the restart when the Brazilian picked up a Lacazette through ball, sped by his defender and beat Fabianski with a lovely finish to give Arsenal the lead.
Coufal brought down Lacazette just inside the area to pick up his second yellow and be sent off, but the France international had his spot kick saved by Fabianski and West Ham stayed in touch with the hosts — albeit playing a man down for the remainder of the match.
Disappointing as they were, West Ham were justifiably angry at referee Anthony Taylor’s decision to show Coufal a second yellow card despite replays showing he had played the ball before sending Lacazette tumbling for the penalty.
Smith Rowe then beat Fabianski with a low line drive to the near post from just outside the penalty area to send the home supporters into rapturous applause as Arsenal continued their recent good form in England‘s top flight.
The result leaves Arsenal on 29 points from 17 games, while West Ham slipped to fifth, one point behind the Gunners.