The Australian has a strong Premier League pedigree and Cech knows he must be at his best to retain his place.
Cech said: "We brought Mark in. Everybody knows he's one of the best goalkeepers you can get. He's a goalkeeper who can play every time.
"You have no idea what you're talking about in terms of goalkeepers, because everyone was saying 'we need better back-up'.
"You've never seen them training, you've never seen them working.
"There are many goalkeepers playing at different teams who don't have the quality of Hilario and Turnbull.
"They kept me always under pressure. I did my best always to play and I did so.
"Ross wanted to play, so that's why he tried his luck and I think he will have a successful season with someone else."