Arsenal started with Eddie Nketiah as a lone striker but his second-half replacement Alexandre Lacazette scored the winner against West Ham.
Alexandre Lacazette came off the bench to score the winner as Arsenal extended their unbeaten Premier League run to eight games with a 1-0 victory over West Ham.
The France international scored only his second league goal of 2020, converting from close range in the 78th minute to clinch three points for Mikel Arteta's side, who struggled to break down a battling West Ham team before Lacazette's second-half introduction.
The best chances of the afternoon before the goal fell to Hammers striker Michail Antonio, who misfired from close range either side of half-time, and Hammers boss David Moyes will be disappointed his side failed to hang on for a precious point towards their battle against relegation.
Arteta started with Eddie Nketiah as a lone striker and failed to capitalise on what little possession came his way, while Gunners top scorer Pierre-Emerick Aubameyang had an uncharacteristically quiet afternoon as he chased his 50th Premier League goal.
The result means Moyes is still without a win in 16 top-flight away games against Arsenal – no manager in Premier League history has taken charge of more winless away games against a single opponent.
West Ham's Jarrod Bowen hit the post with a bobbling 20-yard drive in the second minute amid a slow start from Arsenal, whose first chance came when Mesut Ozil took aim from the middle of the box and drew a good save from Lukasz Fabianski.
Sokratis Papastathopoulos hit the top of the crossbar with a header after Pierre-Emerick Aubameyang teed him up as Arsenal began to turn the screw on a West Ham side content to sit back.
But the Gunners were found lacking in the final third and five minutes before half-time Issa Diop's knock-down to Antonio should have led to the first goal, only for the Hammers striker to fire wide from close range when it looked easier to score.
West Ham continued to press after the interval, and it took a one-handed reaction save from Bernd Leno to keep Antonio from scoring with a free header before Arteta sent on Lacazette in an attempt to inspire his side.
The change did not immediately lift Arsenal, who breathed a sigh of relief after Bowen broke clear only to fire straight at Leno, but moments later came the breakthrough.
Aubameyang's drive looped up into the air and Ozil headed it gently down to Lacazette, who gleefully tucked it home from close range and celebrated after a lengthy VAR check for offside.
Leno made a superb save to deny Sebastien Haller from close range as West Ham sought a quick response, but the hosts survived the scare and closed out the victory.
What does it mean?
Arsenal are just three points outside the top five and a season that once looked set for misery at its conclusion could yet end with European qualification. West Ham have nine league games left to save themselves from relegation, but if they continue to perform at the level they did here, they have every chance of beating the drop.
Bowen verging on brilliant
Twice Bowen went close to grabbing the elusive goal and his pace from midfield caught Arsenal's defenders flat-footed. The former Hull City player looks a fine acquisition.
Pepe lacking end product
Too often this season Arsenal have been deprived of opportunities by Nicolas Pepe's wastefulness and he squandered possession that should have led to chances in either half.
Key Opta facts
- Arsenal's eight-game unbeaten run is the longest in the Premier League at present, comprising of four wins and four draws.
- West Ham have lost each of their last six Premier League away games, their longest such run on the road since a run of eight between August-December 2006, when they were beaten in eight straight.
- Arsenal have kept three clean sheets in their last four Premier League games, as many as they achieved in their previous 23 fixtures in the competition.
- Since the start of last season, Arsenal have scored 16 Premier League goals from substitutes, more than any other side in the competition. Lacazette has scored four of these – no other player has scored more.
- All seven of Lacazette's Premier League goals for Arsenal this season have been scored at Emirates Stadium, the highest 100% home scoring record in the division this term.
Arsenal will face champions Manchester City at the Etihad Stadium on Wednesday evening, while West Ham's next game sees Moyes' men entertain Wolves on March 15 at London Stadium.