Arsenal's Scottish defender Kieran Tierney (left) celebrates after scoring the opening goal during their English Premier League match against West Bromwich Albion at The Hawthorns stadium in West Bromwich, central England, on January 2, 2021.
The one way traffic continued after the break and some comical West Brom defending led to the third as Semi Ajayi smashed a dangerous cross off his own post and the ball broke to Lacazette to apply a simple finish.
Moments later another raid from Tierney down the left teed up Lacazette for another finish from point-blank range for his fourth goal in three games.
West Bromwich
Mikel Arteta said the prospects for Arsenal's season are "completely different" after thrashing West Brom 4-0 to complete three Premier League wins in eight days.
