"On Sunday we have a Premiership game and if we win we can get our confidence back and be positive. That is the good thing about football.
"Sometimes, straight away you have the chance to show that this was just one bad moment and we are a team who still have to work hard, learn to listen to the manager and be at the level we were before."
Chelsea coach Claudio Ranieri is also confident that whatever team he decides to field on Sunday, they will demonstrate their character.
"I am sure that we will show a good reaction at Middlesbrough," he said today.
"We did not play that badly in the first half against Besiktas and had chances to go in front.
"It didn't happen that way unfortunately and once Besiktas had taken the lead they closed down the space and made it very difficult for us.
"If you make even a small mistake at Champions League level you are punished but this was only our first defeat after 10 matches and I know my players have good character.
"Unfortunately, besides losing the match we have also lost William Gallas and Celestine Babayaro with injuries."
With Emmanuel Petit also doubtful, Ranieri looks certain to revert to a four-man defence on Sunday, with Wayne Bridge coming in for Babayaro and Glen Johnson likely to replace Gallas.
It means more changes in front of Chelsea goalkeeper Carlo Cudicini but the Italian remains unruffled by the continued uncertainty about Ranieri's line-up.
"It doesn't really matter who is playing," he said. "We know each other pretty well by now.
"What we have to do now is try and stick together as a group of players. We knew we had to lose sometime and although it's disappointing, our Champions League group is still wide open.
"Sometimes a wake-up call can be a good thing."
Middlesbrough will be without Joseph-Desire Job after the Cameroon international injured a knee in training while defender Gareth Southgate is unlikely to have recovered from a groin injury in time to be considered.
Ranieri, however, could be up against Spanish midfielder Gaizka Mendieta who could return from injury. The pair worked together at Valencia.
Middlesbrough v Chelsea, Riverside Stadium, Sunday, 2pm (live on pay-per-view)
