Chelsea dropped points in the Premier League for the first time under Graham Potter after producing a flat performance in a 0-0 draw at Brentford.
Goalkeeper Kepa Arrizabalaga continued his excellent form to keep the hosts at bay in West London, but a much-changed Chelsea side failed to carve out clear-cut chances during Wednesday's frustrating draw.
While Potter remains unbeaten in seven games with Chelsea in all competitions, the result saw him lose his perfect Premier League record with the Blues, who missed their chance to close in on the top three.
Chelsea remain seven points adrift of leaders Arsenal after failing to break down Thomas Frank's Bees, whose defensive organisation came to the fore in an impressive display.
Kepa made a strong save from Ivan Toney's header as Chelsea withstood a flurry of early Brentford corners, before Conor Gallagher limped off after just 15 minutes in a blow for the Blues.
The Spanish goalkeeper bettered that stop with a terrific reflex save after 33 minutes, clawing another Toney header away from goal after the striker latched onto a second ball in Chelsea's penalty area.
David Raya made his only save of the opening half from Cesar Azpilicueta's low drive two minutes later, before Bryan Mbeumo nodded straight at Kepa after the restart.
Chelsea improved following the introductions of Raheem Sterling and Christian Pulisic, but their offensive woes were summed up by Kai Havertz shooting straight at Raya after finding space in the area.
Kepa stood firm once again to stop Toney's low effort with eight minutes remaining, as both defences refused to be beaten in an even affair.Chelsea host Manchester United in a huge Premier League clash on Saturday, while Brentford travel to struggling Aston Villa the following day.
