The Baggies were forced to make an early change after James Morrison appeared to pull a hamstring after being beaten by Mikel, and was replaced by Craig Gardner after only seven minutes into the game.
The game wore on until the masked Cesar Azpilicueta put the Premier League champions in front after 20 minutes when he connected with a Branislav Ivanovic cross-field pass, to set the home fans in a cheery mood.
The lead wasn’t to last too long however, as the substitute, Craig Gardner scored a beauty 13 minutes later from approximately 22 metres, shooting straight into the bottom left corner, following a pass from Darren Fletcher.
Then West Brom almost went ahead when Jose Rondon received a pass and shot goalwards from 19 metres, only for his effort to miss the target by just a whisker.
Chelsea continued to dominate into the second half and went ahead again in the 73rd minute when Gareth McAuley turned in a Willian cross into his own net and the game seemed all but sewn.
James McClean had other ideas, however, as he put West Brom right back into thw game with an 86th minute equalizer to tie the game at 2-2.