ROME -- Three thoughts on Roma's 3-0 win over Chelsea at the Stadio Olimpico in the UEFA Champions League.
When these two teams played out a thrilling 3-3 draw at Stamford Bridge a fortnight ago, Antonio Conte admitted that Chelsea had never controlled proceedings despite taking -- and then surrendering -- a 2-0 lead. Fortunes were reversed at Stadio Olimpico, but Roma were not so generous.
A breathless opening minute was the match in microcosm: Moments after Pedro fired tamely at Alisson after being played clean through by Tiemoue Bakayoko, Aleksandar Kolarov and Edin Dzeko, the former Manchester City men who tormented Chelsea at Stamford Bridge, combined again to undo Antonio Conte's men inside 40 seconds.
The Bosnia and Herzegovina international's header back to the edge of the penalty area from a clipped ball forward fell perfectly for Stephan El Shaarawy, who reacted quicker than Marcos Alonso and slammed a sensational shot beyond Thibaut Courtois.
Chelsea proceeded to carry the greater threat for much of the first half, with Eden Hazard panicking the Roma defence every time he jinked infield and stinging the palms of Alisson three times in the first half.
But while Hazard was the visitors at their most incisive, Alvaro Morata rendered them toothless. The Spain international went into this match having to answer questions about his commitment to Chelsea, but emerged with his lengthening goal drought the greater concern.
The best chance of the first half fell to Morata, who blasted over unmarked in the six-yard box after Pedro had deflected Kolarov's attempted clearance into his path. Soon after he was too slow to react as Marcos Alonso delivered a pinpoint cross first time from a trademark David Luiz switch of play.
Chelsea's striker insists his hamstring is fully healed, but he remained a shadow of the striker who lit up the Premier League in August and September at Stadio Olimpico, as his goalless run extended to five matches.
At the other end, Roma were ruthless. El Shaarawy capitalised on Antonio Rudiger's concentration lapse to glance in Radja Nainggolan's deep cross and double their first-half lead, and a Diego Perotti screamer on 63 minutes put them out of sight. The scoreline would have been worse on Chelsea had the Argentine not blasted over from a counter-attack soon after.
Only at this point did Conte turn to Michy Batshuayi, scorer of eight goals in his previous 10 matches for club and country. Chelsea's head coach has valid concerns about the Belgian's ability to be the "reference point" for the attack but, given Morata's struggles, perhaps greater trust is required.
The only positive on a torrid night for Chelsea was Atletico Madrid's failure to beat Qarabag at home, leaving their passage to the Champions League knockout stage inconvenienced rather than seriously endangered.
Earlier this month Conte revealed that Chelsea are training "70 percent less" than last season, and suggested that significantly less time spent drilling tactics at Cobham could be responsible for his team's defensive decline.
Constantly shifting personnel -- both due to injuries and suspensions to Gary Cahill and Luiz -- has also hindered Conte's efforts. But the Italian is not one to hide behind excuses and whatever the cause of Chelsea's defensive malaise, Roma's big night at Stadio Olimpico underlined that it is getting worse rather than better.
The pre-match talking point was Conte's conclusion that it would be "stupid to risk" a less-than-100 percent N'Golo Kante with Manchester United next up, but the France international's absence was not the primary factor in Roma's first two goals.
El Shaarawy's spectacular finish for the opener concealed the fact that Alonso was too slow to react to a loose ball created by a free header given up to Dzeko, and Rudiger embarrassed himself on his return to Stadio Olimpico by bizarrely opting to let Nainggolan's cross run past him for the second.
Individual errors and miscommunications were so rare that they were shocking under Conte last season, but the surprise is wearing off. Chelsea have kept only five clean sheets in all competitions this season and, Kante or no Kante, there are broader structural issues to be addressed.
Roma have kept seven clean sheets in 10 Serie A matches this season and coach Eusebio Di Francesco has been criticised for prioritising defence over attack.
This, however, is not the team Chelsea saw in a startlingly open 3-3 draw at Stamford Bridge a fortnight ago, and nor was it here, as Roma took the Premier League champions apart with a game plan as ambitious as it was ruthless.
Beyond his goals, Dzeko looks a man reborn in Rome. Flanked by El Shaarawy and Perotti racing forward and finishing with this level of confidence, Di Francesco has a rounded and dynamic frontline capable of troubling much better defences than Chelsea's proved to be here.
Daniele De Rossi was a calming influence at the heart of midfield, complemented by the relentless energy of Nainggolan and craft of Kevin Strootman, and once Kostas Manolas is fit enough to regain his starting spot it's not hard to imagine Roma's proud Serie A defence translating to the European stage too.
Add that all together and you might have a Champions League contender. You certainly have a team equipped to frighten any team in a competition marked by Real Madrid and Bayern Munich's early-season struggles.
Di Francesco has successfully transformed the mentality of a club that had won just two of their last 17 Champions League matches entering this season. Roma are unbeaten through four games of this campaign in a group that includes, by reputation at least, two genuine European heavyweights.
Liam is ESPN FC's Chelsea correspondent. Follow him on Twitter: @Liam_Twomey.