British number two Kyle Edmund said "you have to believe" when asked if he can win the Australian Open.
The 23-year-old beat Italy's Andreas Seppi 6-7 (4-7) 7-5 6-2 6-3 to reach his first Grand Slam quarter-final.
He will play Grigor Dimitrov in the last eight, and sees no reason why he cannot make further progress.
"That's why I'm in the quarter-finals - because every time I step on the court, I believe I'm going to win," said Edmund.
"It's no different now. The next opponent, I take it one step at a time.