LONDON, Oct 28 (Reuters) - Brentford snatched a 2-0 win away at Chelsea on Saturday as the expensively assembled Blues failed to turn possession into goals once again and were punished by a thumping header from defender Ethan Pinnock and a last-minute breakaway goal by Bryan Mbeumo.
The west London derby defeat was yet another setback for Chelsea coach Mauricio Pochettino, whose side had shown signs of putting a poor start to the season behind them recently with two wins out of three and a 2-2 draw against Arsenal last weekend.
"The frustration is so massive," Pochettino told talkSPORT radio, saying a strong first-half performance gave way to a lack of calm after the break.
"We are doing our job, we are happy here," the Argentine said. "We need to be clinical and score more goals. This is what is missing... We need to keep believing."
Chelsea started on the front foot but for all their buzzing around Brentford's penalty area, they created few chances before Pinnock, undetected by Chelsea's defence, connected powerfully with an Mbeumo cross in the 58th minute.
The Blues poured forward in search of an equalizer but in the 96th minute goalkeeper Robert Sanchez, venturing up for a corner, was caught out when the visitors broke away and Mbeumo rolled the ball into an empty net.
Chelsea have now won only one of their last 13 home league games, a dismal run stretching back into last season when they fired managers Thomas Tuchel and then Graham Potter.
Blues winger Noni Madueke almost broke the deadlock in the first half when his curling shot hit the crossbar with 10 minutes on the clock. Defender Marc Cucurella shot straight at Mark Flekken after a lofted pass by playmaker Cole Palmer.
But Brentford soaked up everything Chelsea could throw at them with centre forward Nicolas Jackson, back in the starting 11 after an injury, unable to provide much of a threat.
Brentford's third league win at Stamford Bridge in as many seasons meant that they leap-frogged their neighbours into 10th spot, while Chelsea dropped to 11th ahead of the rest of the weekend's fixtures.
The latest failure to find the back of the net will intensify speculation that Chelsea will invest heavily again in the January transfer window, having already spent around 1 billion pounds on new players since a U.S.-led takeover in 2022.
One name linked to the club is Brentford and England centre forward Ivan Toney who scored 20 times in the league last season but who is currently serving an eight-month ban for breaching betting rules. That ban expires in January.