STUTTGART: Karolina Pliskova will face world number one Ashleigh Barty in the quarter-finals of Stuttgart's WTA clay-court tournament after seeing off Jelena Ostapenko in a three-set battle on Thursday.

Pliskova, the sixth seed, recovered from losing the first set in a tie break by firing down 21 aces, 10 of which came in the last set alone, for a 6-7 (7/9), 6-4, 6-3 second-round win.

"I like spending time on this court," joked Pliskova, the 2018 Stuttgart champion, after needing just under two and a half hours to claim victory.

"It was a far better performance from me," she added, having laboured in Wednesday's victory over lucky loser Tamara Korpatsch.

Thursday's result was almost identical to Pliskova's win over Ostapenko in the 2018 quarter-finals in Stuttgart when the Czech went on to capture the title.

Former French Open champion Ostapenko hurled her racquet in anger in the second set, while Pliskova broke one of hers as she regained control of the match.

"It always helps me when I break a racquet," the Czech said.

Pliskova, ranked ninth in the world, plays top seed Barty of Australia in the last eight Friday.

"She's on a good run and has won a few tournaments, but I have nothing to lose," added Pliskova.

Barty, who won a pre-Australian Open tournament in Melbourne and the Miami Open earlier this month, breezed into the quarter-finals Wednesday by overpowering Laura Siegemund following a first-round bye.

She is using the Stuttgart event as part of her preparations for next month's French Open, where she won her first Grand Slam title in 2019.

She sat out the 2020 tournament at Roland Garros because of the Covid-19 pandemic.