Russian fourth seed Mirra Andreeva overcame compatriot Ekaterina Alexandrova 7-6(7/4), 7-6(7/3) on Thursday to reach the China Open semi-finals, where she will face Czech Nikola Bartunkova in a young-guns showdown at the WTA 1000 event in Beijing.

French Open champion Andreeva, 19, broke 19th seed Alexandrova to move 2-0 ahead before falling 5-3 behind in a fluctuating opening set as both players struggled to hold serve.

The teenager, however, recovered to edge the tiebreak.

Andreeva seemed firmly on course for victory in the second, leading 4-1 and serving for the match at 5-3 before Alexandrova, 31, staged a late fightback to force another tiebreak.

Andreeva took control of the tiebreak with a forehand winner for a 3-2 lead and won five of the final six points to seal victory and reach her first Beijing semi-final.

“Even when I had an advantage in the second set leading 5-2, I felt like she was still pressuring me,” Andreeva said in her post-match interview.

“I felt like she was playing better, and I did not take my chances. I could have played more aggressively.

“But what a match this was. I’m super happy with how it went. She played unbelievably today, and I’m very happy to get my very first win against her.”

Bartunkova crushes Muchova

Earlier on Thursday, 26th seed Bartunkova reached her first WTA 1000 semi-final with a dominant 6-3, 6-0 victory over fellow Czech and seventh seed Karolina Muchova in 67 minutes.

Bartunkova, 20, controlled the contest from start to finish, winning five consecutive games to begin the match and the final seven games to complete the rout of Wimbledon runner-up Muchova, who is 10 years her senior.

“I follow her (Muchova) a lot,” Bartunkova said. “I have a similar style to hers — playing a lot of drop shots, volleys.”

Bartunkova continued her impressive run in Beijing after stunning four-time Grand Slam champion Aryna Sabalenka in the last 32.

Bartunkova will make her top 30 debut after the tournament.

“For sure (I did not expect it) before this tournament,” Bartunkova told a press conference. “I played a lot of practice matches with top players — (Iga) Swiatek, (Coco) Gauff and others. Maybe it helped a little bit. It was one week before the tournament.

“I tried to play a lot of practices, lot of matches. I think that was the reason I had good preparation for this tournament. I had confidence. But honestly, I didn’t expect these results.”