Astana (Kazakhstan),  World No.6 Stefanos Tsitsipas registered a 6-3, 6-2 win over Hubert Hurkacz to reach the semifinal of the Astana Open, here on Friday.

The Greek rallied to win a gripping first set, then broke late in the second for the victory. With this, Tsitsipas powered into his ninth semifinal this season and improved his ATP head-to-head lead against Hurkacz to 7-2. This, however, marked the first straight-set result in their past seven duels.

Tsitsipas has yet to be broken in three matches at the ATP 500 in Kazakhstan, although it looked like he would concede his first set of the week when his fellow Top 10 star in the Pepperstone ATP Rankings held five set points in the first-set tie-break.

On the third one of those, the Greek player looked in particular trouble. With Hurkacz serving, Tsitsipas threw up a defensive lob after the Pole's forehand approach. But Hurkacz, so assured on smashes previously in the set, erred wide.

Two more set points came and went for the seventh seed before Tsitsipas capitalised on his lone opportunity when Hurkacz's backhand passing shot strayed wide.

"(In) Most of those situations, I was not the fortunate one serving. I was still able to break through and get back fighting, and it was very, very emotional to get that first tie-break after having thrown my body on the court," Tsitsipas said post-match, referring to the set points.

"It was a very good moment to finish it off and get the tie-break," he added.

His good form in tie-breaks in Astana thus continued, after Tsitsipas won both against Italian qualifier Luca Nardi in the second round.

Hurkacz had done well to force the tie-break given he saved all eight break points he faced in three successive service games. Clutch serving proved key, as the Pole produced seven first serves, which prompted seven returns that did not clear the net. On the other one, Hurkacz served and volleyed behind a second serve.

It countered Tsitsipas' own service games. At one stretch in the first, the Greek won 11 straight points behind his delivery. Overall, Tsitsipas only lost 10 points on serve. Hurkacz was bound to be reeling early in the second but steadied early. At 3-4, though, he relinquished serve from 40/15 in the second set's only break-point chance.

"I got that break I was looking for in one of the very last moments of the match, which gave me such a relief after trying to break him for so long," said Tsitsipas.

Tsitsipas then comfortably served it out, helped by a net cord on his first match point. In deep concentration, he initially did not know the match finished.

Third seed Tsitsipas carries a 5-4 ATP head-to-head record into his semi-final clash with Andrey Rublev, who began the quarter-final day by topping Adrian Mannarino 6-1, 6-2.

"He strikes the ball very hard. But I'm going to concentrate on my game. I'm going to be well prepared and visualise it before," said Tsitsipas about his clash with Rublev.

Tsitsipas is bidding for a maiden ATP 500 crown, having lost all eight of his finals at 500s. Despite the defeat, Hurkacz jumped one spot into eighth in the ATP Live Race To Turin courtesy of his run in Astana this week, as the Pole attempts to qualify for the ATP Finals for the second time.

Hurkacz's day is not over in Astana, where he and partner Jan Zielinski later face Mannarino and Fabrice Martin in the doubles semi-finals.