Rome - Stephan El Shaarawy scored a brace as AS Roma mauled Chelsea 3-0 to claim top spot in Champions League Group C on Tuesday at the expense of the English champions.
The rematch in Rome's Stadio Olympico after a 3-3 thriller in London two weeks ago did not disappoint the 55 000 crowd as Chelsea coach Antonio Conte was frustrated on his return to Italy.
El Shaarawy rifled in two first-half goals - the first after less than a minute and the second nine minutes before the break - with Argentine Diego Perotti adding a third on 63 minutes.
A second win in four games moves the Romans closer to the last 16, thwarting Chelsea who had been hoping to seal a spot in the knockout rounds with two games to go.
Eusebio Di Francesco's side are the only unbeaten side in the group and now have eight points from four games, one point ahead of Chelsea, with Atletico Madrid third on three points after being held 1-1 by Qarabag.
"It was a great evening for our fans who also deserved this victory. But it mustn’t stop here, this game must be a starting point. We're closing in on something important."
Conte's Chelsea were a shadow of the team that played at Stamford Bridge earlier this month.
"I didn't see anything positive in the second half, it was really bad," said Conte.
"Roma showed a hunger and desire to beat us. They really deserved this victory."
French midfielder N'Golo Kante, who has just returned from a hamstring injury, was left out by the Italian, along with Nigerian Victor Moses as Greek defender Kostas Manolas started on the bench for Roma.
El Shaarawy and Perotti backed up Edin Dzeko in the Roma attack with Chelsea counting on the trident of Eden Hazard, Alvaro Morata and Pedro.
After an opening burst the hosts were ahead after just 38 seconds when Dzeko nodded down and El Shaarawy blasted into the back of the net past a stunned Thibaut Courtois.
"These are evenings you remember for your whole life," said El Shaarawy. "Your first Champions League brace doesn't happen every day."
Hazard - who scored a brace in the first meeting along with Dzeko - was omnipresent early for Chelsea with Alisson saving twice at the near post, Morata also missing an opportunity in front of goal for the Blues.
But after going close a second time, El Shaarawy broke through again on 36 minutes following a long ball from Radja Nainggolan.
A Tiemoue Bakayoko header looked dangerous but Alisson dived to clear four minutes before the break.
Perotti got the third after the break following a Cesc Fabregas error in midfield to pile the pressure on Chelsea, who could thank Belgian keeper Courtois for pulling off some key saves including from a searing Manolas header.
And Perotti could have made it 4-0 minutes later as unmarked he fired over an empty net.
Fabregas came off midway through the second half with Danny Drinkwater getting his Champions League debut for Chelsea.
But it was all Roma, as Nainggolan was kept out by Courtois, along with a Dzeko header from the resulting corner.
Conte is now under increasing pressure as his side sit fourth in the Premier League ahead of next weekend's game against Manchester United.
"We were unlucky in the first half. The second half was bad all round," said Conte.
"We have to understand that this season will be very difficult if we don't have the right attitude and if we don't fight until the end."
He added: "I honestly don't care about the Qarabag result, we have to think about how to improve and to have the new players as soon as possible."
Roma next travel to Atletico Madrid with Chelsea facing the long trip to Qarabag in Azerbaijan.