Rafa Benitez's winless start as Chelsea manager worsened on Saturday as West Ham came from behind to beat their London rival 3-1 in the Premier League on Saturday.
Juan Mata put Chelsea ahead in a fluent first-half performance, but the European champions collapsed after former striker Carlton Cole equalised in the 63rd minute with a contentious header.
But there was no disputing the late goals from West Ham substitutes Mohamed Diame and Modibo Maiga, which extended Chelsea's winless run in the league to seven matches.
"The first half I think we deserved more goals, the second half we didn't deserve too much,'' Benitez said.
Benitez has drawn twice and lost once in his three matches since replacing the popular Roberto Di Matteo with the task of revitalizing Chelsea's stuttering season.
It had started so well at Upton Park for Chelsea when Mata scored in the 13th minute for the team's first goal under Benitez and the club's first in five hours, 34 minutes.
Fernando Torres cut ball back from the right to Mata, who swept in his eighth goal of the season.
But it had no effect on the Chelsea fans' hostility to Benitez's appointment, with a 'Rafa Out' banner emerging and the by now familiar chant of 'There's Only One Di Matteo'.
Blues on top
On the pitch, though, Chelsea were in control during their high-tempo start.
The Blues should have been further in front after a speedy counterattack in which Ramires launched down the right flank to set up Torres. But the Spain striker put the ball over the crossbar to leave him without a league goal in two months, while Eden Hazard also curled a shot over.
Kevin Nolan thought he had equalised for West Ham with an overhead kick, but it was ruled out after James Collins was penalised for a push on Ivanovic.
A double save from West Ham goalkeeper Jussi Jaaskelainen then prevented Chelsea from extending their lead.
Victor Moses weaved his way down the left flank before squaring to the unmarked Mata, whose first effort was blocked, as was his follow-up.
Cech were booked for handling outside the area but he made amends by tipping over Nolan's header only moments after the free kick.
Chelsea were looking shaky at the back and West Ham looked to exploit it, putting the visitors under siege at the start of the second half.
Chelsea center back Gary Cahill was kept busy, blocking shots from Diame, who replaced Gary O'Neil at halftime, and Nolan.
While West Ham were now the more fluent outfit, the hosts were fortunate that their equaliser was given.
Carlton Cole climbed on Ivanovic, clasping the defender's neck, as he rose to meet Matt Jarvis' cross and power the header past Cech.
Amid the Chelsea protests, midfielder John Obi Mikel was booked. Chelsea tried to produce an immediate response, but Hazard's shot was blocked by Jaaskelainen.
Benitez's decision to replace Hazard with Oscar was met with chants of 'You Don't Know What You're Doing' as a first away game under the new manager provided no respite from the hostile Chelsea fan base.
Cech was keeping Chelsea in the game, making a low save from Winston Reid's header and then denying Jarvis.
From the resulting corner, it took a headed goal-line clearance from Ashley Cole to keep out Reid's effort.
But West Ham finally broke through in the 86th when Cole squeezed the ball back to Diame, who stabbed the ball past Cech.
The third goal came in the third minute of stoppage time. Ashley Cole gave the ball away and Maiga picked up possession before teeing up Matt Taylor, whose initial shot was saved - but Maiga sent the follow-up past Cech.