Last season's beaten semi-finalists Atletico Madrid and AS Monaco find themselves dumped out of Europe's premier footballing competition along with German giants Borussia Dortmund. Everybody's favourite underdogs were out without putting up a fight.
While the Arnautovic's strike boosted his side's hopes of climbing out of the bottom three, it dealt a severe blow to Chelsea's hopes of defending their title.
Premier League: Liverpool's jittery performance in Chelsea draw exposed their structural deficiencies
In spite of gaining a point against the defending champion, Liverpool have much to ponder and improve.
Chelsea rode their luck to salvage a 1-1 draw at Liverpool thanks to Willian's late leveller, while Manchester United cut Manchester City's Premier League lead to five points with a 1-0 win over Brighton on Saturday.
"Roma proved to have more hunger, more desire, more will to fight and to beat us. We lacked everything," complained Conte.
Premier League: Over-dependence on Alvaro Morata haunts Chelsea as Eden Hazard, Pedro, Willian go missing
Manchester City's 7-2 drubbing of Stoke City on Saturday made them the first team to score 29 goals in the opening eight games of a top-flight campaign since Everton in 1894-95
Nabil Fekir's last-gasp free-kick delivered three crucial points to Lyon in Ligue 1 on Friday as their captain sealed a 3-2 home win over champions Monaco.
Premier League: Manchester City showcased their title-wining credentials in tactical win over Chelsea
In Aguero and Jesus, Manchester City probably have the best strike partnership in the Premier League. With De Bruyne and Silva pulling the strings in midfield ahead of a stable defence, they have showcased their title credentials.
Chelsea enjoyed a triumphant return to the Champions League after a year out on Tuesday, thumping the competition’s debutants Qarabag 6-0.
Champions League: Lionel Messi's brace helps Barcelona beat Juventus; Manchester United, Chelsea win big
Lionel Messi netted twice in Barcelona's convincing 3-0 victory over Juventus, while Paris Saint-Germain, Manchester United and Chelsea also won big in the Champions League on Tuesday.
A rare N'Golo Kante goal on his return to Leicester gave Premier League champions Chelsea a 2-1 victory at the King Power Stadium on Saturday.
Premier League: Antonio Conte insists Chelsea still can attract world's best despite transfer window woes
The feeling remains that Conte isn't completely satisfied by the way Chelsea hierarchy handled the transfer market and he was quick to point out he had only limited involvement in recruitment.
Premier League champions Chelsea have bolstered their squad with a transfer deadline-day move for Italian right-back Davide Zappacosta.
Premier League: Manchester United well placed to challenge on all fronts this season, says Nemanja Matic
Nemanja Matic remained tight-lipped, however, about his move from Stamford Bridge which prompted many to conclude that Chelsea manager Antonio Conte had made a big mistake by letting him go.
England midfielder Alex Oxlade-Chamberlain is set to join Premier League champions Chelsea from Arsenal, according to British media reports on Monday.
Kylian Mbappe was left on the bench as Radamel Falcao scored twice in Monaco's 6-1 trouncing of Marseille in Ligue 1 on Sunday.
Antonio Conte said he would be happy for Chelsea to creep up on the rails in the Premier League title race following their clinical 2-1 victory over Tottenham Hotspur.
Premier League: Antonio Conte must stabilise Chelsea or risk season of disillusion and disintegration
As at the majority of Premier League clubs, Chelsea don’t tolerate defeat. Losing isn’t an option. Conte needs a magic syringe that will inject some hardiness and life into a seesaw Chelsea, a club at the confluence of many debilitating factors - or else, he risks a summer of disillusion and disintegration.
Premier League: Chelsea coach Antonio Conte says club can't look for excuses after shaky start to season
Antonio Conte has warned troubled champions Chelsea not to look for excuses after their turbulent start to the season.
Tottenham Hotspur host Chelsea in the first Premier League game at Wembley as their season-long tenancy at the national stadium gets underway on Sunday.