After a seven-match winless run in the top flight prior to Christmas, the Gunners defeated Chelsea at home and Brighton and Hove Albion away and were full of confidence against Sam Allardyce's struggling side.

Fine first-half goals five minutes apart from Kieran Tierney and Bukayo Saka – the first a sublime solo strike, the second a flowing team move – made a mockery of tricky conditions and moved Arsenal out of sight.

Alexandre Lacazette added a comical clincher and later doubled his tally as a third straight victory boosted Mikel Arteta's men up to 11th, now suddenly looking up the table rather than back towards the relegation scrap in which the Baggies remain mired.

Arsenal had quickly assumed control in the falling snow, although Matt Phillips might have done better than shoot straight at Bernd Leno from a rare West Brom opening.

The visitors heeded that warning and soon led when Tierney pushed the ball past Darnell Furlong on the left flank, then checked back inside to beat his opponent again and finally beat Sam Johnstone with a curling right-footed shot.

The swift second was equally impressive, albeit an entirely different kind of goal as Emile Smith Rowe moved the ball on to Saka and continued his run while Alexandre Lacazette took possession and fed a pass back into his path. Through on goal, Smith Rowe unselfishly squared to find Saka once more for a simple finish.

A flag denied West Brom an early second-half response as Matheus Pereira ran offside before his drive against the post landed back at the feet of Callum Robinson with the goal gaping.

Instead, a bizarre third went Arsenal's way when Semi Ajayi awkwardly volleyed against his own post and recovered to block Smith Rowe's follow-up but watched Lacazette lash in the rebound, the Frenchman netting in a fourth consecutive match in all competitions.

He had another four minutes later, kneeing in Tierney's drilled cross, with West Brom ultimately fortunate to escape further punishment.