Saturday's defeat to Manchester City ended the Premier League leaders' FA Cup run at the fifth round stage, and Belgium international Hazard was disappointed with his side's display at the Etihad Stadium - where they had won 1-0 in the top flight just 12 days earlier.
Chelsea are now fighting for two trophies this season, with the Londoners sitting a point clear at the top of the Premier League ahead of their UEFA Champions League last 16 clash with Galatasaray.
And Hazard knows an improvement on their performance at the Etihad is needed if they are to be in contention for success come May.
"Collectively we were worse because individually we were not good," he told Chelsea's official website. "That can happen.
"Especially in the first half we could have better with some phases of play. Maybe it was a lack of confidence but it was not our day.
"We never managed to find a solution once they had scored. We were just not in the game.
"We have to keep working and move on from this match because we have a very important league game next weekend and that's our focus now."
Chelsea host Everton in the league on Saturday, before travelling to Istanbul for the first leg of their European tie on February 26.
