Chelsea let slip a one-goal lead but battled back in the final 10 minutes to earn a share of the spoils in a thrilling 2-2 draw against Swansea City at the Liberty Stadium.
In a match full of talking points, particularly in the second period, the Swans turned the game on its head before seeing a second win on the bounce against their opponents slip away late on.
Diego Costa scored twice for his team either side of a Gylfi Sigurdsson penalty and Leroy Fer strike, meaning that Antonio Conte's winning start to life at Chelsea has come to an end - but it could have been much worse for the Italian.
The hosts went with a new five-at-the-back system from the off, which they failed to adjust to early on as Willian was allowed to drift into the box and test Lukasz Fabianski with a stinging shot.
Chelsea were seeing plenty of the ball in the opening quarter of the match, but prior to their goal the Swans' backline did not have a great deal to keep out.
Star man Costa's breakthrough strike 18 minutes in gave the Blues a platform to build on, however, as the home side failed with three attempts to clear Branislav Ivanovic's deep cross into the box.
Federico Fernandez was most at fault, twice heading straight into the air which allowed Oscar to tee up his teammate to coolly tuck the ball out of Fabianski's reach.
Less than two minutes later Eden Hazard was able to ease his way past four players and into the box, only to be thwarted by Fabianski at the front post with only the keeper to beat.
Cesar Azpilicueta was the next visiting player to have an attempt, again looking to beat the Polish stopper at his near post to no avail, and that forced Francesco Guidolin into action as a back five became a back three shortly before half time.
Neil Taylor was the man to be sacrificed on his first league start of the season, which he did not take too kindly to as he left the field, and the change of system did not pay any immediate dividends as only a poor Costa miss from two yards out prevented the Welsh outfit from falling further behind.
The big talking point in the opening stages of an explosive second half came early on when Jordi Amat, fresh off the back of receiving a yellow card, lunged in on Ivanovic rather needlessly but avoided further punishment.
Despite being on top pretty much throughout, Chelsea were made to pay for falling to extend their lead when City launched a rare counter-attack which led to a penalty kick being awarded.
Sigurdsson chased down a pass and got to the ball ahead of Thibaut Courtois, who was himself lucky to avoid being dismissed, and the Iceland international blasted the ball down the middle to become Swansea's record Premier League scorer.
The hosts used that goal as momentum to push on and they were ahead less than three minutes later when Gary Cahill was caught in possession by Fer, who raced through and prodded past Courtois to change the complexion of the game completely.
Things really came to life from that point on, as Hazard fluffed his lines in a promising position moments later before Costa was seemingly bundled over by Fabianski, but replays showed that referee Andre Marriner made the right call when waving play on.
Chelsea have already recovered from a goal down this term at Watford, and they did all they could to claw themselves back level as Oscar curled a shot towards the top corner for Fabianski to help on its way over.
Conte, staring a first defeat as Chelsea boss right in the face, brought on Cesc Fabregas and Victor Moses as the game entered its final 15 minutes, and the pressure soon became unbearable for the hosts.
Oscar was involved in all Chelsea's best moments, heading wide from a promising position and dragging another shot wide, but then the leveller did arrive when Costa acrobatically found the back of the net from close range after the Swans again failed to deal with a cross into the box.
Costa had another shot on goal saved in the closing stages and Fabregas's close-range shot was also blocked aside, yet there was to be no fifth goal in an entertaining match as the teams were made to settle for a point apiece in South Wales.
Daniel Lewis
