MELBOURNE—Barbora Strycova, who defeated Caroline Garcia in the third round of the Australian Open, will now face 22-time Grand Slam singles champion Serena Williams.

“I'm looking forward to that match. That's why you train,” said Strycova. “That's why you work hard, to play these matches on these stages and against the best one. She's a powerful player, and I'm so small. I would have to work hard and I have to run a lot."

The 30-year-old Czech is now ranked a career-high No. 16. A week ago in Sydney, she upset Ekaterina Makarova, Roberta Vinci and Caroline Wozniacki before losing to Agnieszka Radwanska in the semifinals. At the Australian Open, she has also beaten former Top 10 player Andrea Petkovic.

Strycova has matched her best result at the Australian Open—last year, she upset Garbine Muguruza in the third round before falling to former No. 1 Victoria Azarenka. She has only played Williams twice before in singles, losing at the 2012 Australian Open and that year’s Wimbledon tournament.

"It's going to be tough one, but I am also a tough player to play,” said Strycova. "I don't give anything for free, and I fight all the time. I will try my best. And I will have to work hard and play my best tennis to beat Serena, because she is amazing player. She know how to play these matches.”

Strycova has also been talking with Petra Kvitova, who was attacked with a knife in a home invasion late December. Kvitova wants to come back to the tour, but she hasn’t set a return date.

“She will be very strong, because she's a very strong person. And she will fight it back,” Strycova said. “She will try to work hard, and she's a great person. So she will be all right. She will be strong coming back here.”