(Photo credit: Aaron Doster-Imagn Images)

Sara Bejlek is through to her first career WTA 1000 semifinal, and she got there the hard way.

The 20-year-old Czech player continued her run of upsets at the Cincinnati Open by rallying past 20th-seeded Madison Keys 3-6, 6-4, 7-6 (5) in the quarterfinals on Friday at Mason, Ohio.

Keys was the third major champion Bejlek defeated in the tournament. She stunned world No. 1 Aryna Sabalenka in the previous round, and she also downed Barbora Krejcikova in the second round.

Bejlek will square off with another major champ in the semifinals when she opposes fourth-seeded Coco Gauff, a 6-2, 6-2 winner over 10th-seeded Marta Kostyuk of Ukraine on Friday.

Bejlek is pursuing her second career WTA title after she prevailed at Abu Dhabi, United Arab Emirates, in February.

She said of her self-confidence, 'I think it's increasing during the season. We had a big talk with my team a couple weeks ago and since that moment I feel that it's going quite well. I'm getting better in believing in myself and improving physically on the court.'

The final stats between Bejlek and Keys were nearly identical: 71% first-serve points won by Keys to 70% for Bejlek; 47% second-serve points won by both; 7 of 10 break points saved by both.

The turning point came in the middle of the second set. Keys was up a set and a break at 6-3, 3-1, but Bejlek won four of the next five games, breaking serve twice to level the match.

Keys also was up 4-2 in the decisive tiebreaker, but she lost three of her final four service points.

Gauff is through to her third consecutive semifinal, having lost in that round at Wimbledon and in Toronto. She won 63% of her service points to just 42% for Kostyuk.

Part of Gauff's success was built on advances to the net.

'I didn't realize how good I was at it until Wimbledon,' Gauff told reporters. 'Everyone has been telling me to come to the net more. Actually, Chris Evert has been texting me sometimes to come to the net more. And I tell her yeah, I'm going to, and then I just don't. I finally did at Wimbledon and I won so many points that way.

'And obviously here, there's just a big difference when you're able to finish the point at the net.'

Gauff and Bejlek are set to face off for the first time.

'Sara's a great player,' Gauff said Friday. 'I've heard of her before, but at first, I watched her a lot in Abu Dhabi this year. She won that title. She's such an athletic, fast player, really makes you earn every point.'

--Field Level Media