Antonio Conte admitted his concerns and urged Chelsea to “dig deeper” after they slumped to a 3-0 defeat to Roma in the Champions League on Tuesday.
Stephan El Shaarawy scored after 39 seconds and then pounced on an Antonio Rudiger error to make it 2-0 after 36 minutes.
Diego Perotti struck a fine third after 63 minutes as Roma climbed above the Blues to take top spot in Champions League Group C.
A win would have seen Chelsea advance to the knockout stages, but instead Conte was left ponder how to respond in Sunday’s Premier League clash with Manchester United, live on Sky Sports Premier League.
Conte said: “This season we have to dig very deep if we want to be competitive and fight for something important. If we are not ready to dig deeper, we can have this type of game.
Ian Wright and Matt Le Tissier said on The Debate that all is not right at Chelsea this season and manager Antonio Conte looks unhappy
“This season will be very difficult if we don’t understand quickly the right way that we have to go.
“Last season we showed great hunger, great will to do something of importance. Last season we won the league and did a miracle. If we think that only because our name is Chelsea and the opponent has fear for the name Chelsea, I think this is not the right way.
“We must find the hunger that we showed in all last season and in this season sometimes. We have to try to find the strength to understand and to use this loss in the right way.”
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Chelsea looked to be coasting in Group C after following up their opening 6-0 win over Qarabag with victory at Atletico Madrid.
But after conceding six goals in two games with Roma, Chelsea need points in Azerbaijan before the final group clash with Atletico.
Conte insisted he was content with Chelsea’s first-half performance, but the second was “really bad”.
“I actually believe that in the first half we played a good match,” he added. “We created many chances and were unlucky not to take them.
“What I’m most disappointed about was the performance in the second half when Roma had more hunger, more desire, more fight to beat us and clearly deserved this win.
“The second half was really bad, bad for a team like us. I didn’t see positive things.”
Roma boss Eusebio Di Francesco, meanwhile, was overjoyed by his team’s performance.
“We really deserved this,” he 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.”