SHANGHAI (AFP) -- Sebastian Korda reached his first Masters semifinal as he held his nerve to tame fast-rising fellow American Ben Shelton 6-7 (10/12), 6-2, 7-6 (8/6) in Shanghai on Thursday, Oct. 12.

The 26th seed finally sealed a thrilling quarterfinal on his sixth match point and plays Poland's 16th seed Hubert Hurkacz for a place in Sunday's final.

The draw has opened up for the 23-year-old Korda as he closes on a second ATP title.

Top seed Carlos Alcaraz was turfed out in the last 16 to follow Daniil Medvedev -- beaten by Korda -- Holger Rune, Stefanos Tsitsipas and Jannik Sinner out the exit door.

Korda was more relieved than anything else afterwards, having let slip five match points in the deciding-set tie break.

"It was a super-high level from both of us and thrilled to get through an especially tricky tie break," said Korda, whose father Petr reached two in the world and won the Australian Open in 1998.

"That's probably one of the biggest things of having a father who played tennis -- to kind of understand certain moments.

"I think in those certain moments you got to stay really calm. You can have such a big lead like that and you could just completely panic or get super down on yourself and just get lost."

With the court roof closed because of rain in Shanghai, the first set went to a tie break after the young Americans exchanged breaks in the 11th and 12th games.

US Open semifinalist Shelton, who uncorked a serve clocked at 236 kilometers (150 miles) per hour earlier in the set, had Korda on the back foot throughout a gripping tie break.

The pressure finally told when the recently turned 21-year-old Shelton unleashed an ace on his fifth set point that Korda could only watch whizz by.

Korda recovered to break Shelton's big serve at the start of the second set and raced to level the quarterfinal at one set all.

Korda broke the 19th seed at the start of the deciding set and then dug himself out of a hole, saving three break points to extend his lead to 3-1 and then 4-2.

But Korda, whose only previous ATP title came in 2021 in Parma, allowed Shelton back in again and they went to another tie break.

Korda just about held his nerve in the tie break to belatedly seal an absorbing encounter in just under three hours.

In the first quarterfinal, Hurkacz similarly fought back to defeat unseeded Hungarian Fabian Marozsan 4-6, 6-1, 6-3.

The Shanghai Masters is back after four years following the pandemic and has witnessed a succession of shocks.

There is only one player from the world's top 10 left in the draw in the form of seventh-ranked Russian Andrey Rublev.

The fifth seed faces 32nd seed Ugo Humbert of France in the quarterfinals while 18th seed Grigor Dimitrov -- who turfed out Alcaraz -- plays 22nd seed Nicolas Jarry.

World number one Novak Djokovic skipped the tournament.