Sanchez sinks West Brom to settle Arsenal nerves

Booed off following Sunday's 1-1 draw at home to Crystal Palace, Arsenal delivered a more clinical display at the Emirates Stadium as Sanchez took his tally to five goals in four games, and 16 for the season, with a first-half brace from outside the box.

After consecutive draws, Arsenal manager Arsene Wenger will have been relieved to see his team record their 500th Premier League victory, which lifted them above Manchester City and into third place.

The result also served to keep Arsenal's title challenge mathematically alive, but with leaders Leicester City 10 points above them, the north London club's chief objective over their final four games will be to hold off fifth-place Manchester United, who they lead by four points.

West Brom, who have lost three successive games for the first time this season, remain 10 points clear of the relegation zone, but they are unlikely to feel completely safe until they register another victory.

Rumours of a mass boycott by disgruntled Arsenal fans were not fully borne out, but it was possible to discern some 10,000 bare seats as this re-arranged fixture kicked off.

One of three Arsenal changes from the stalemate with Palace saw Aaron Ramsey make his first start in a month after a thigh injury and the Welsh midfielder played a part in the hosts' sixth-minute opener.

The goal was all Sanchez's own work, however, as he gathered Ramsey's square pass, brilliantly spun away from Sandro and drilled a low shot into the bottom-left corner.

- Iwobi, Elneny penalty appeals -

A sequence of set-pieces briefly offered West Brom hope and after Sanchez survived a handball appeal when he flicked the ball against his own hand inside the Arsenal box, Gareth McAuley hit the bar with a header from James McClean's in-swinging corner.

But Arsenal were soon back on the front foot and West Brom goalkeeper Ben Foster almost embarrassed himself by allowing a tame Mesut Ozil shot to creep between his legs, forcing Craig Dawson to clear off the line.

In the 38th minute Sanchez made it 2-0, flashing a free-kick past a flat-footed Foster.

West Brom manager Tony Pulis made a double-change at half-time, sending on Jonas Olsson and Salomon Rondon for James Chester and Sandro and switching to a bolder 4-4-2 formation.

But the second half's main talking points occurred in the visitors' box as first Alex Iwobi and then Mohamed Elneny avoided bookings for going down in search of penalties, despite referee Jon Moss having shown Leicester City's Jamie Vardy a second yellow card for diving last weekend.

While McClean put a header straight at home goalkeeper Petr Cech and Ramsey produced an impeccably timed challenge to halt Stephane Sessegnon, the rest of the game was a tale of rolling Arsenal attacks.

Foster saved from Ozil and, with his face, Olivier Giroud, while Ramsey put an attempted chip over the bar and substitute Joel Campbell fired wide.