Chelsea survived an almighty scare to beat promoted Reading 4-2 in a topsy-turvy Premier League clash at Stamford Bridge.
The European champions appeared to be cruising when Frank Lampard converted an 18th-minute penalty to cap a dominant early spell for the hosts.
But a Pavel Pogrebnyak header - his first goal for the club - levelled on 25 minutes, with the Championship champions edging ahead soon afterwards when a blunder from Petr Cech allowed Danny Guthrie to open his Reading account.
Chelsea were struggling and looked bereft of ideas but, after a smart tactical switch by Roberto Di Matteo midway through the second half, they drew level when another goalkeeping error from Adam Federici saw Gary Cahill net from distance.
The West London side then took the lead in controversial circumstances with 10 minutes remaining when an offside-looking Fernando Torres tapped in Ashley Cole's low cross after a lovely passing move.
Reading went gung-ho in search of a late equaliser and, in the fifth minute of injury time, Chelsea added a fourth when Federici was stranded after coming up for a corner, Branislav Ivanovic rolling the ball into the empty net after Eden Hazard had broken free.
The victory means Chelsea go top of the fledgling Premier League for a few days at least, although that could change at the weekend. Reading boss Brian McDermott, meanwhile, must decide whether he can trust Federici at this level after the Australian cost his side two possible victories in succession.
The Wednesday evening clash, moved from next week due to Chelsea’s European Super Cup duties, was a chance for the Blues to play their first competitive home fixture following their Champions League heroics last May.
They started like contenders, dominating possession from kick-off as Reading’s touches were limited to the occasional interception and a Federici save from Ramires.
Torres almost opened his season account with a wonder goal, nutmegging and rounding defenders for fun before seeing his finish blocked by a sliding Alex Pearce, but the hosts were able to take the lead soon afterwards when Hazard tricked Chris Gunther into a rash challenge, referee Lee Mason pointing to the spot.
Lampard solidified his position as second-highest penalty scorer in Premier League history with a smart drive into the bottom left, his 39th from the spot, although some way off record holder Alan Shearer (56).
But from that point onwards Chelsea fell to pieces, a combination of poor defending and a fading midfield contributing to a speedy demise.
That Reading had been forced to attack after conceding was largely irrelevant – both their goals were eminently avoidable.
The first came thanks to hesitant defending from John Terry, who was dragged out of position to cover Cole but failed to close down Gareth McLeary. His fine cross picked out Pogrebnyak, who easily beat Cahill to a flicked header that evaded Cech and nestled in the top left.
That was shoddy, but Reading’s second was unforgivable. Terry gave away a needless free-kick on the left-hand edge of the Chelsea penalty area, but Cech should have easily held on to Guthrie’s daisy cutter – not only did the Czech keeper fail to gather his shot, he palmed it into his own net in what will be considered one of the howlers of the season.
Pearce should have added a third before half time but he somehow failed to make contact with an excellent Ian Harte free-kick, despite being unmarked with just Cech to beat; Torres repaid the favour at the other end, although it was a more difficult header from between Pearce and Kaspars Gorkss.
Chelsea were toiling badly, in shell-shock following that quickfire Reading double, but also struggling in the middle of the park with both Ramires – only recently recovered from illness – and Juan Mata below par.
But Di Matteo should be credited for a pair of substitutions which changed the balance of the game: first Oscar replaced compatriot Ramires, immediately giving the hosts more dynamism in midfield; then Daniel Sturridge came on for John Obi Mikel, adding a more direct width to Chelsea’s attacks and crucially allowing Hazard to adopt a more central role.
The Belgian won Chelsea’s first game of the season at Wigan, and he did so again – even when his team struggled, the former Lille playmaker was fleet of foot and thought as he won free-kicks for fun.
He was now making the team tick and, having moved into the middle, forced a decent stop from Federici after a long passing move that sparked the turning point in the match.
After good play from Oscar, Torres saw another effort blocked, this time by Pearce, and seconds after Sturridge entered the fray Chelsea were level.
Cahill has a fondness for getting forward and scoring spectacular long-range efforts, but Federici should have stopped his swerving drive on 70 minutes – the error was not as bad as Cech’s, nor his own against Stoke at the weekend, but he got two strong hands on the ball and should have kept it out.
A Chelsea victory was inevitable as they lay camp in the Reading half, Mata firing a low drive through the yellow shirts with Federici a spectator, but the finish fizzing wide of the post.
They snuck ahead soon afterwards but there was a heavy dose of offside about Torres when he crept in unmarked to tap home a low Cole cross that managed to evade Reading’s defence and keeper.
It was a wonderful team passing move - Mata's through ball to Cole a particular delight - but close inspection of the replays showed Torres to be a fraction offside, although it was tight.
With 10 minutes remaining, Reading were forced into an unnatural all-out attack mode and they could have drawn level after some good late pressure, Harte’s late free-kick deflected behind for a corner.
From that final set piece Chelsea completed the comeback, Federici giving chase after Torres cleared the corner but left no chance against Hazard, who zipped away down the right before unselfishly handing Ivanovic an easy finish, Gunther the only Reading player able to get back in time but outnumbered by the hosts.
It added a sheen to an unconvincing win but with two wins in two matches Chelsea have laid a marker as they attempt to convert last season’s cup form into a convincing league threat.