A brace from James Morrison was not enough to earn Albion a point against Champions Chelsea.
Morrison missed an early penalty before Chelsea raced into a two-goal lead.
The midfielder pulled one back for the Baggies before the visitors snatched a third just before half time.
After John Terry had been shown his marching orders, Morrison headed Albion's second.
Tony Pulis left out striker Saido Berahino out of Albion's matchday squad after speculation around his future continued. But Callum McManaman and new-boy Salomon Rondon were handed their first starts of the season. James McClean was also recalled to the starting XI; but who caught your eye?
Jonas Olsson won the Watford accolade with 42.9% of the votes.
Vote for your Albion Man of the Match here.