Match ends, Arsenal 2, West Bromwich Albion 0.
Alexis Sanchez scored twice as Arsenal beat West Brom to strengthen their hopes of a top-four finish.
The Gunners had drawn their previous two games but Sanchez settled the nerves with a neat finish on the turn from outside the area.
West Brom's Gareth McAuley hit the bar with a header but that was as close as they came to a goal.
And Sanchez's driven free-kick secured the win for Arsenal, who move up to third, five points behind Tottenham.
The win helps ease concerns the Gunners could miss out on the top four - they are now four points clear of Manchester United in fifth.
Sanchez provides a much-needed spark
Striving to stay in the top four is a far cry from how Arsenal's fans would have imagined this season finishing considering their position on New Year's Day, when they were top of the table.
The north London club were ideally positioned to challenge for a first Premier League title in 12 years, but a run of just five wins in 2016 prior to the visit of West Brom all but ended their hopes.
A disappointing 1-1 draw at home to Crystal Palace on Sunday left the Gunners 13 points behind leaders Leicester and some fans had made their discontent clear with boos at the final whistle at the weekend.
Fan apathy was evident in the number of empty seats at Emirates Stadium on Thursday, and there was an eerie atmosphere when the game got under way.
An early goal was needed to ease the tension and Sanchez duly stepped up to deliver with a finish of real quality. The forward received a pass from Mesut Ozil and turned Sandro before firing beyond Ben Foster.
The Chilean was at his marauding best and he continued to torment West Brom before deservedly scoring a second, driving a free-kick through the West Brom wall.
Arsenal untroubled by blunt Baggies
Under Tony Pulis, West Brom have hardly been prolific. They have scored just 50 goals in 51 games and have had the fewest shots on target in the Premier League this season with 93.
Add that to the fact they had lost all but one of their nine previous Premier League trips to Arsenal, and a victory for the visitors looked a tall order.
Their best chances came from set pieces. McAuley rattled the bar from a corner when the score was 1-0, while Salomon Rondon missed a near open goal from another corner midway through the second half.
From open play they carried no threat but with the Baggies 15th and 10 points clear of trouble, their job is largely done.
How did ref Jon Moss do?
This game was the first for referee Jon Moss since his controversial performance in the 2-2 draw between leaders Leicester and West Ham on Sunday.
Moss awarded two penalties in that game, and also gave Foxes striker Jamie Vardy a second yellow card for diving.
On Thursday, Moss waved away a West Brom appeal for a penalty when Sanchez appeared to handle inside the area, and also took no action when Arsenal's Mohamed Elneny went down easily inside the area despite there being no contact by a defender.
He issued just the one yellow card and that was to McAuley after the Baggies defender held Olivier Giroud just before half-time.
Man of the match - Alexis Sanchez (Arsenal)
What the managers said
Arsenal boss Arsene Wenger: "We did the job in a serious way. We played well technically and the only regret is we should have scored more goals.
"The early goal helped us not be be anxious about the consequence of the result.
"We are in a position where it depends on us to finish in the top three but we want more and we have to fight to do that and if possible do more."
West Brom manager Tony Pulis: "We didn't play as well as we can. We had too many players off it, which you can't do at Arsenal.
"The players have given me everything this year. We have played well at all of the big teams but not tonight. Sometimes you have to take defeat on the chin."
The stats you need to know
- Arsenal have now won 500 Premier League games, the second team to reach the milestone in the competition (Manchester United have 584 wins).
- The Baggies have won just one of their past 12 Premier League away games (D5 L6).
- The Gunners have scored in all 20 of their Premier League games against West Brom - the best 100% record in the division.
- Arsenal scored as many goals from outside the box on Thursday as they had in their 33 previous Premier League games this season (two).
- Tony Pulis has lost all eight of his Premier League visits to Emirates Stadium.
Arsenal travel to struggling Sunderland on Sunday, while West Brom are at Tottenham on Monday.
- 17SánchezSubstituted forWalcottat 86'minutes
- 11ÖzilSubstituted forCampbellat 86'minutes
- 45IwobiSubstituted forCoquelinat 82'minutes
- 23McAuleyBooked at 41mins
- 4ChesterSubstituted forOlssonat 45'minutes
- 30Guimaraes CordeiroSubstituted forRondónat 45'minutes
- 14McCleanSubstituted forGardnerat 65'minutes
- Jonathan Moss
- Shots on Target
Second Half ends, Arsenal 2, West Bromwich Albion 0.
Foul by Joel Campbell (Arsenal).
Craig Dawson (West Bromwich Albion) wins a free kick in the defensive half.
Offside, Arsenal. Joel Campbell tries a through ball, but Olivier Giroud is caught offside.
Foul by Nacho Monreal (Arsenal).
Stéphane Sessegnon (West Bromwich Albion) wins a free kick in the defensive half.
Attempt missed. Olivier Giroud (Arsenal) right footed shot from the centre of the box misses to the right. Assisted by Joel Campbell.
Attempt saved. Olivier Giroud (Arsenal) left footed shot from the left side of the box is saved in the top left corner. Assisted by Joel Campbell.
Attempt missed. Joel Campbell (Arsenal) left footed shot from the left side of the box misses to the right. Assisted by Aaron Ramsey.
Substitution, Arsenal. Joel Campbell replaces Mesut Özil.
Substitution, Arsenal. Theo Walcott replaces Alexis Sánchez.
Attempt missed. Claudio Yacob (West Bromwich Albion) right footed shot from outside the box misses to the left.
Aaron Ramsey (Arsenal) wins a free kick in the attacking half.
Foul by Claudio Yacob (West Bromwich Albion).
Substitution, Arsenal. Francis Coquelin replaces Alex Iwobi.
Alexis Sánchez (Arsenal) wins a free kick on the right wing.
Foul by Jonny Evans (West Bromwich Albion).
Attempt blocked. Craig Gardner (West Bromwich Albion) right footed shot from outside the box is blocked. Assisted by Salomón Rondón.
Foul by Laurent Koscielny (Arsenal).