San Francisco Frontiers - Teenager Andreeva seals China Open semi-final with Bartunkova

Andreeva, the 19-year-old fourth seed, is the favourite for the tournament in Beijing now that a series of upsets have knocked out her more esteemed rivals.

The French Open champion dropped just three points to grab a two-game lead but still needed a tie-break to edge 28th-ranked Alexandrova in the first set.

Both players struggled to extend rallies in a sparsely populated stadium as they tumbled into another tie-break.

Andreeva found the breakthrough with a masterful forehand to go 3-2 ahead, then held her nerve, dropping just one more point before crossing the finish line.

"I am very happy that we finished this match, because I knew if it (went) to the third set it's going to be really tough for both of us," Andreeva said.

"She played unbelievable," the teenager said of her 31-year-old opponent. "What a match."

Earlier, world number 34 Bartunkova stunned her Czech compatriot Karolina Muchova 6-3, 6-0 as she sealed the win in just 66 minutes.

The 20-year-old won five consecutive games in 19 minutes in the first set as her seventh-seeded opponent struggled to respond.

Muchova saved five set points but it was not enough to hold back Bartunkova, who had already ousted second-seeded Aryna Sabalenka from the tournament in Beijing.

She raced into to another five-game lead in the second set and gave Muchova no chance of a reprieve, forcing her into firing long to seal a win she described as a "dream come true".

"Honestly I don't know. It was (an) unbelievable match," Bartunkova said on court.

"She's a great player and also a great human being.

"It was a really tough match today, but I was just trying to put my best tennis, and I did it."

On Friday, China's Zheng Qinwen plays Ukraine's Elina Svitolina, and Poland's Iga Swiatek faces Belgium's Elise Mertens, each gunning for a semi-final spot.

R.Baker--SFF