Didier Drogba gave new Chelsea boss Avram Grant the perfect tonic with a crucial second-half strike that earned a Champions League win in Valencia.
Chelsea captain John Terry leads the celebrations for Joe Cole's opener
Chelsea captain John Terry played with a mask on a fractured cheekbone and led from the front in a defiant display.
Valencia took the lead after nine minutes when David Villa raced clear to beat Petr Cech.
But Joe Cole scrambled an equaliser before half-time then passed for Drogba to slot home after 70 minutes.
Terry, as expected, took his place in the line-up wearing protection on the injury he sustained against Fulham on Saturday.
Valencia gave Chelsea a scare inside the first 40 seconds, with David Silva firing narrowly over the top.
It was brief reprieve for Chelsea as Valencia were rewarded for their brisk opening with a goal after nine minutes.
A loose ball bounced off Michael Essien into the path of Villa, who showed real pace to escape Terry and slide a composed finish past Petr Cech.
Cech made a crucial save after 20 minutes, blocking from Joaquin after good work by Fernando Morientes.
The worth of the save was emphasised seconds later as Chelsea broke to level and stun Valencia.
Florent Malouda was the architect, exchanging passes with Drogba before sliding in a perfect cross for Cole to get a touch just ahead of Emiliano Moretti to score.
Joaquin was posing problems for Chelsea, and he should have restored Valencia's lead when the ball rebounded off Ricardo Carvalho into his path, but he shot over the top.
There was a worrying moment for Chelsea on the stroke of half-time when Drogba pulled up clutching his hamstring, but he recovered and emerged after the interval.
Villa thought he had put Valencia back in front after 55 minutes when he was played in by Morientes, but his finish past Cech was chalked off for offside.
Chelsea had shown real composure after the break, and they got their reward when Drogba put them in front with 20 minutes left.
Joe Cole was the creator, winning possession before delivering a brilliant through ball with the outside of his right foot for Drogba to race clear of Raul Albiol and score.
Drogba then tested Valencia keeper Timo Hildebrand with a 20-yard free-kick as Chelsea grew in confidence.
Valencia, inevitably, mounted a fierce assault in the closing minutes but Chelsea were not to be denied and claimed the points.
Chelsea manager Avram Grant:
"You saw the attitude in the last two weeks, it has been difficult, but it was good. I keep telling you I'm very happy with the attitude.
"It's nice to be at the top. We came here to win the game. I think we want to do it and in the right way. To come back from 1-0, the second half we dominated, I'm happy.
"All the staff and the players have done a very good job. We did it the right way."
Valencia: Hildebrand, Miguel, Albiol, Helguera, Moretti, Joaquin (Arizmendi 89), Marchena, Albelda (Baraja 74), Silva, Morientes (Zigic 69), Villa.
Subs Not Used: Canizares, Sunny, Angulo, Alexis.
Goals: Villa 9.
Chelsea: Cech, Ferreira, Terry, Carvalho, Ashley Cole, Makelele, Essien (Sidwell 84), Obi (Alex 89), Joe Cole, Drogba, Malouda (Kalou 85).
Subs Not Used: Cudicini, Shevchenko, Pizarro, Belletti.
Goals: Joe Cole 21, Drogba 71.
Ref: Roberto Rosetti (Italy).