Karolina Pliskova believes the WTA Finals are wide open after becoming the first player to book a semi-final berth in Singapore.
Pliskova's first victory over Fed Cup team-mate Petra Kvitova was enough to secure her progression from the White Group, the world number eight winning 6-3 6-4.
She will be joined in the knockout stages by Elina Svitolina, while the qualifiers from the Red Group will be decided until Friday.
Sloane Stephens leads the way but any of the players within the group could still progress, with Pliskova expecting a tough battle in the final four whoever she comes up against.
"All the matches are tough, so you don't really have any guess who's going to win," she told a media conference.
"To the last point it's not clear. And there is not really that big difference in the rankings, so everybody can beat everybody here.
"I think everybody has a chance to win. Doesn't matter which ranking you are. Doesn't matter you didn't play for a year. Doesn't matter how bad you feel.
"There is no time limit, so you can play till whatever time, and even if it's 2-6, 1-5, you can still win the match."
She added: "I feel good. I was pretty positive even after the match that I lost against Svitolina. I think my game is just completely fine. There is no reason to panic or there is no reason to just feel bad about something. I think my shots are pretty solid, so I can play anywhere.
"It means a lot, and for sure, to get it to go to semi-finals after beating [Kvitova], it's just special."
Kvitova was not too downbeat on her performance at the end-of-season event despite losing all three group matches, posting a positive message on Twitter after Thursday's loss.
"This season was always going to end with a smile on my face," she said. "No matter what.
"Was it a perfect week? No. Was it an incredible season? Yes.
"See you at the Fed Cup final."
