The ramifications will be nothing like as severe for Roberto Di Matteo as they were for Andre Villas-Boas, who was sacked after Chelsea lost here in March, but this still felt like a significant defeat for the Italian. It is now four Premier League games without a win for Chelsea – their worst run since Di Matteo took over from Villas-Boas – and there are inevitable comparisons to be drawn with previous seasons, when winter's onset has frozen Chelsea's title aspirations.
Having picked a much-changed team because of the midweek internationals, rather than Tuesday's Champions League game against Juventus in Turin, Di Matteo was forced to endure the sight of West Brom continuing their remarkable start to the season with a sixth home win in seven matches that lifts them to the dizzy heights of fourth. Shane Long was outstanding, the Irishman scoring the opener, when he exposed David Luiz's poor positioning to head in James Morrison's centre, before setting up the second for Peter Odemwingie with a superb cross that the Nigerian nodded past Petr Cech. Eden Hazard had hauled Chelsea level shortly before the interval with a header from Cesar Azpilicueta's deep cross.
Long's performance was all the more impressive because he was playing 24 hours after being told that his grandmother had passed away.
The striker paid tribute to her by unveiling a message under his shirt after he scored – 'Rest in peace Nan' – and he flew back to Ireland immediately after the game for her funeral. "I ran out of words to describe him a number of weeks ago," said Steve Clarke, the Albion head coach who was up against his former club. "Shane produced another fantastic performance in what has been a difficult week for him." The contrast with the striker leading Chelsea's front line could not have been greater. Fernando Torres once again looked out of sorts and he was withdrawn in the second half, when Di Matteo sent on Juan Mata and Oscar.
Daniel Sturridge was thrust further forward but the goal that Chelsea coveted never came. Boaz Myhill denied him with two superb saves before Sturridge drilled a presentable chance beyond the far upright in the final three minutes.
In a final act of desperation, Cech dashed into Albion's penalty area for a corner in injury-time but the goalkeeper failed to get on the end of Mata's cross and the game was up for Chelsea. Di Matteo acknowledged that Chelsea's poor form was "a concern", bemoaned the poor defending that Albion ruthlessly punished, and admitted he could be forced to abandon the attacking principles that earned so much praise earlier in the season.
"We are playing a little bit different [this season] and we might have to go back a little to be able to win games, to make sure that first and foremost we don't concede, Di Matteo said. "Maybe it's a time where we might have to change a little. Maybe [we need to] sacrifice a little bit of the attacking options to go a bit more defensive."
As well as the Juventus game, which Chelsea need to avoid defeat in order to be sure of keeping their destiny in the own hands in terms of reaching the Champions League knock-out stage, there is the small matter of a home game against Manchester City in the Premier League five days later. Chelsea desperately need a remedy for their malaise.