Chelsea manager Antonio Conte says he and his players must take responsibility for their 3-0 defeat by Roma in the Stadio Olimpico.
Stephen El Shaarawry's two first half goals left Chelsea with a mountain to climb in the Italian capital. Diego Perotti's 63rd minute strike from outside the box sealed Chelsea's first defeat in the Champions League this season.
Qarabag's 1-1 draw at Atletico Madrid in the other Group C fixture means Conte's side have a four-point gap on the Spanish side and one win from their final two games will see the Blues qualify for the knockout stage.
That was of little comfort to Conte who was disappointed with his side's desire compared to Roma's.
"The second half was a really bad performance because Roma showed more desire and more will to fight to win the game," Conte told BT Sport.
"I'm very disappointed with our second half and we all have to take responsibility.
"When you concede three goals, you must be worried because it means something doesn't work.
"Tonight was a bad night for us. I only want one night like this and we must work together this week."
Goalkeeper Thibaut Courtois, beaten six times in two matches against the Serie A side, urged his team-mates to respond positively against Manchester United at Stamford Bridge on Sunday.
"We felt good at half-time because we played well, but I don't know why in the second half we dropped our fighting spirit and our mentality," he said.
"We have to fight back on Sunday and show the fans this was an off day.
"It's hard to say what the problem is. Last season, there were games where I had nothing to do and other games I had four or five saves.
"This season every game is a hard game and we have to find the mentality of clean sheets and not conceding goals."
Roma boss Eusebio Di Francesco, meanwhile, was overjoyed by his team's performance.
"We really deserved this," Di Francesco said.
"Our fans deserved this great win, and it's no coincidence I played many players today who helped get us into this competition.
"We have gained self-belief. There are more fights to come to establish ourselves, but we've proved we can play against any team with this mindset and collective effort."