The Blues are on an underwhelming run in the Premier League, losing to West Brom on Saturday as they warmed up to face the Italian champions.
"Losing games isn't acceptable here and people are upset when we do. Sometimes things need to be said," the former Bolton man told reporters.
|28/1||Gary Cahill is 28/1 with Bet365 to score the first goal in Juventus v Chelsea
"When you lose games it does knock confidence but we have strong characters and it's important not to dwell on it too much.
"All the lads are aware of what we have to do tomorrow and hopefully we'll be well prepared to go and do it."
Cahill also move to defend team-mate David Luiz, who has come under fire recently after some unconvincing displays in the Blues' back line.
"David Luiz is so comfortable on the ball and has great ability - you don't captain Brazil if you're not a top footballer," the centre-back declared.