The Gunners dominated Tony Pulis’ side from the first whistle in north London on Thursday night, with their Chilean attacker netting a first-half brace to seal a vital win.
Alexis Sanchez scored twice as Arsenal tasted victory in the Premier League for the 500th time with a 2-0 win over West Brom at the Emirates Stadium.
The win moves Arsenal to 3rd with 2 points ahead of Manchester City and 4 points adrift of Manchester United. While Westbrom are now 15th on the log.