Cahill started Chelsea's 2-0 League Cup triumph over London rivals Tottenham at Wembley on Sunday but the England international centre-back has been forced to take a backseat to French youngster Zouma, who has partnered John Terry.
After a strong start to the season, Cahill was dropped on the back of a disappointing performance as Chelsea lost 5-3 at Tottenham on New Year's Day.
Cahill has been out in and out of the team since then, missing the second leg of Chelsea's League Cup tie with Liverpool, and Premier League matches against Manchester City, Everton and Burnley.
But after returning to the starting line-up for Chelsea's successful outing at Wembley, Cahill believes he still has a feature at the club.
"I have proved it time and time again. I proved it when I was at Bolton and I got the England call-up. I was told 'you can't play for England, you're at Bolton'," Cahill said.
"I proved them wrong. I came to Chelsea and it was 'oh you can't play Champions League, you can't do this, you can't do that' and I proved them wrong.
"It's that fire in your belly. Although you'd wish not to have it, it [dealing with criticism] is probably what has got me to where I am today. This is no different. I will come out the other end without a shadow like you see today.
"That [the 5-3 defeat] was a bad day at the office for the team. Certainly since I have been at the club we have been fortunate enough to have positive results against Tottenham.
"It was said before Sunday's game that that result would have no reflection on the final and so it proved. I use it as motivation to prove people wrong time and time again.
"You are not a robot. Up until the halfway point in the season it was no problem – but I have come through it time and time again. It's not the first time I've had have a dip in levels of performance."
