The Blues stopper has been a mainstay in the side since his arrival in London back in 2004, but a high-profile mistake against Paris Saint-Germain on Wednesday has seen Cech's place in the side questioned.
Boss Jose Mourinho has said Courtois will return to London in the summer, which has led many to speculate that Cech's days are numbered at Stamford Bridge.
However, the 31-year-old insists he still has what it takes to succeed in the Premier League, and has staved off competition before to retain his number one jersey.
"The moment I feel I am not good enough to play at the highest level I will stop," Cech told the Daily Mail.
"I would like to continue.
"I had Carlo Cudicini behind me when I came here, the best goalkeeper in the Premier League.
"When Ross Turnbull played for Middlesbrough he was a big English prospect.
"Hilario has always been ready to play, and you can see the difference at Fulham when Mark Schwarzer is there.
"And I'm still playing. This cannot be underestimated."
Courtois has been on loan in Madrid for three years now, and seems settled, but a spot in Chelsea's starting XI could persuade him his future lies in England.
However, despite the impressive form of the young Belgian keeper, Cech admits he can only focus on his own game, and the rest will look after itself.
"If he comes back, and he's better than me, credit to him," Cech added.
"I am not afraid.
"I will still have to do better than whoever else is here to keep my place."