"I could see, I could feel from myself and from the team, that some emotions took over, maybe frustration, maybe disappointment," said Tuchel of his side's display in midweek.
"We have to make sure we are in a different attitude and a different mindset, and in top shape, because we have a big match coming on Sunday."
Tottenham's miraculous comeback from 2-1 down after 94 minutes to win 3-2 at Leicester on Wednesday means Spurs head to Stamford Bridge eight points behind third-placed Chelsea, but with four games in hand.
West Ham, Arsenal and Manchester United also have games in hand on the European champions in the race for a place in next season's Champions League.
A total of 22 Premier League games have been postponed in recent weeks, with playing squads depleted by coronavirus and injuries.
"It's strange to see the fixture and see teams competing for the same area of the table and having four games less," said Tuchel.
"This can lead to a wrong impression that you're comfortably ahead when you are not. So we have to make sure that this stays like this."