Theo Walcott marked his return to the side with a first-half hat-trick as Arsenal raced into a 4-0 lead over West Bromwich Albion at the Emirates Stadium.

The Gunners took the lead inside four minutes through the recalled Walcott, who lashed the ball home with a vicious strike into the top corner.

Arsene Wenger's side continued to push forward and Alexis Sanchez tried his luck despite the angle being against the Chile international, and his effort sailed over the bar.

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Some neat build-up play from the home side saw Mesut Ozil slip in Sanchez, but the former Barcelona man's effort was comfortably held by Boaz Myhill.

Walcott claimed his second on 14 minutes by showing some quick feet inside the area before poking past Myhill.

Jack Wilshere made it 3-0 before the 20-minute mark with a well-struck half-volley that flashed into the top corner.

Walcott was denied his third by a fingertip save from Myhill, before the goalkeeper thwarted Wilshere's effort before the half-hour mark.

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Myhill once again stopped Walcott from chalking up a hat-trick on 35 minutes as the Gunners pressed to extend their advantage.

However, the Baggies stopper was powerless to deny Walcott on 37 minutes as the striker rewarded his manager's faith with a tap-in at the far post, after Santi Cazorla had scuffed a shot into his path.