Diego Costa's stunning finish in the 75th minute masked what was both a difficult match individually and for Chelsea, who came through 1-0 against West Brom at Stamford Bridge to enhance their title challenge.
His strike had similarities with his equaliser against Manchester City, providing relief for his team and manager when the Blues were struggling. Yet again, he came up with an outstanding piece of skill.
Antonio Conte switched formations twice before the goal came and his tinkering proved decisive. Substitute Cesc Fabregas played a ball forward from which Costa used his strength to force Gareth McAuley into an error ahead of applying a stunning finish past Ben Foster.
Visiting boss Tony Pulis will have been devastated to see his side beaten in such a manner. WBA won the midfield battle and kept Costa, Eden Hazard and Pedro quiet - they even arguably created the better chances.
Such was the success of West Brom, Costa had fewer touches than any other Chelsea player around the 60 minute mark and was reduced to his frustrated self from last season.
For much of the match, Chelsea lacked the fluidity of recent weeks but stretched their winning run to nine games. There were signs, though, that WBA had fallen upon a system to stifle Conte's hitherto successful 3-4-3 system.
But the Baggies could not get over the line. Conte has improved the temperament of Costa since the summer, and his improved attitude was vital to Chelsea's success.
The Spain striker showed signs of frustration towards the end of the first half, in which the Blues did not even manage a shot on target until the 41st minute. Again he was the victim of numerous strong challenges - something he should be used to as the player who draws the most bookings from opponents in the Premier League.
But he also showed his match-winning qualities.
As Sergio Aguero serves a four-match suspension after his dangerous foul on David Luiz last Saturday, Costa has grown into the league's most decisive player and he is key to Chelsea title ambitions.