Chelsea squandered two priceless Premiership points against Reading.
Didier Drogba celebrates after heading his second goal
Didier Drogba headed Chelsea in front from Frank Lampard's corner seven minutes before half-time.
But Reading responded after the break and it was no surprise when Leroy Lita headed a deserved equaliser from Glen Little's cross after 67 minutes.
Drogba's header swiftly restored Chelsea's lead, but Reading levelled after 85 minutes, Ashley Cole's clearance flying in off Michael Essien.
Chelsea had twice scrambled late winners at Wigan and Everton in their last two Premiership games but there was to be no reprieve this time as Reading claimed a point.
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Reading's Stephen Hunt, who was involved in the controversial collision that resulted in a fractured skull for Chelsea keeper Petr Cech earlier this season, was left out of the starting line-up.
Chelsea drafted in Andriy Shevchenko and Wayne Bridge for Arjen Robben and Ashley Cole, with John Terry sidelined again with a back injury.
And the champions dominated the opening 45 minutes, with Drogba inevitably the spearhead.
He played in Frank Lampard after only two minutes but his half-hit shot rolled tamely wide.
And Drogba then forced a fine save from Reading keeper Marcus Hahnemann, who dived at his feet to smother a shot after a clever pass from Shevchenko.
Drogba was denied again after 28 minutes when Hahnemann saved low to his left as he flicked on Lampard's free-kick.
But he was not to be thwarted as Chelsea took the lead.
Drogba outmuscled Hahnemann and Reading defender Ibrahima Sonko to head in Lampard's corner.
Reading opened with a much greater sense of purpose and ambition after the break, with Brynjar Gunnarsson's cross deflecting dangerously across the goal after taking a deflection off Ricardo Carvalho.
Steve Sidwell then gave Chelsea keeper Hilario a scare with a right-foot shot that flew into the side-netting.
A sign of Chelsea's struggles came after 57 minutes when Shevchenko, who had again looked desperately off the pace, was replaced by Wright-Phillips.
Chelsea had been totally subdued since half-time and it was no surprise when Reading drew level after 67 minutes.
Little's cross was inviting from the right-flank and Lita dived forward to head past Hilario with ease.
Mourinho responded with an instant double substitution, sending on Mikel Jon Obi and Ashley Cole for Geremi and Bridge.
And Reading's joy lasted only five minutes before Chelsea were in front again, Drogba heading in Wright-Phillips' cross at the far post.
Reading's most reliable marksman Kevin Doyle then wasted a glorious opportunity to restore equality again, shooting wildly over when unmarked from only eight yards.
Steve Coppell's side deserved much credit in the second period and Gunnarsson was again only inches away with another header.
And they equalised in farcical fashion with five minutes left when Cole's attempt to clear Doyle's cross flew past Hilario off Essien.
Chelsea manager Jose Mourinho:
"That was a fair result. We did enough to win because we scored two goals and could have scored more.
"I don't think I can complain about the players. For example the game at Wigan was easy but we made it hard for ourselves. Yes, I had reason to be unhappy with them then.
"But today no because Reading made it difficult for us. When the opponents do well and create problems, you can't complain, only praise the opposition.
"They got a point at Stamford Bridge. Of course we want to win every game and we are never happy to draw, but there is no criticism aimed at my players because they did the best they possibly could."
Reading manager Steve Coppell:
"We had a defined gameplan and the players stuck resolutely to that. I think 1-0 down is a precarious position to be in but we really pushed on.
"There was a real determination in the dressing room. The players were very positive and the momentum was with us for the second half.
"Once we got back in I thought we might have gone on to win the game. We had a bit of fortune for the second goal. We are pleased with the point. We haven't played well recently."
Chelsea: Hilario, Geremi (Mikel 70), Ferreira, Carvalho, Bridge (Ashley Cole 70), Kalou, Essien, Ballack, Lampard, Shevchenko (Wright-Phillips 58), Drogba.
Subs Not Used: Hedman, Diarra.
Goals: Drogba 38, 72.
Reading: Hahnemann, Murty, Ingimarsson, Sonko, Shorey, Little, Sidwell, Harper, Gunnarsson, Doyle, Lita.
Subs Not Used: Federici, Hunt, Oster, Sodje, Ki-Hyeon.
Goals: Lita 67, Essien 85 og.
Ref: A Wiley (Staffordshire).