After winning through to the fourth round of the Australian Open, Victoria Azarenka admitted she was unsure whether she could return to the top of women's tennis following a foot injury that ruined last season.
Former world number one Azarenka claimed a hard-fought 6-4 6-4 win over Barbora Zahlavova Strycova in her third-round tie on Saturday.
The 25-year-old, a two-time Australian Open champion, is unseeded in Melbourne this year and has slipped to number 44 in the rankings.
And, after earning a last-16 clash with 2014 runner-up Dominika Cibulkova, Azarenka said doubts had crept into her mind but she has learnt to deal with them.
"I think it's very normal and very human to be able to have doubts, to question whether you're going to be able to do it or not," Azarenka said.
"But I think the approach to those thoughts is what counts and what brings you to be a champion.
"That's what brought me to all my success that I had in the past, to what I'm doing right now.
"Being able to control those doubts, really fight through them. They're going to come up. You just have to be able to accept that challenge and really grind.
"I think compete, grind, those things what make you work through all those doubts."