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.

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.

(BBC)