Australian No.2 Marinko Matosevic is through to the semi-finals of US National Indoor Tennis Championships courtesy of a straight-sets win over seventh seed Alexandr Dolgopolov.

Matosevic’s impressive run in the tournament continued on Friday with a 6-7 (6-8) 6-2 6-4 victory over the Ukrainian, after he defeated Japan’s Go Soeda and fourth-seeded American Sam Querrey in the earlier rounds.

World No.53 Matosevic will meet Kei Nishikori in the semi-finals.

Nishikori won their only prior meeting in Brisbane earlier this year.

Fifth-seeded Nishikori of Japan cruised past top-seeded Marin Cilic 6-4 6-2.

Croatia’s Cilic had saved three match points in his previous match against Igor Sijsling, but couldn’t find the answer against Nishikori, who had just four aces compared to a dozen for Cilic but won 69 per cent of points on his serve.

“I was dominating with my serve,” said the 23-year-old Nishikori, who reached the semi-finals in Brisbane in January but retired from that match against Andy Murray with a knee injury.

Since then, he has reached the fourth round of the Australian Open.

“It’s getting better every match … little by little,” Nishikori said of his game.

In women’s action in this combined ATP and WTA Tour event, big-hitting Sabine Lisicki of Germany set up a title showdown with Marina Erakovic.

Lisicki, the third seed, fell behind in each set but dug deep for a 7-5 7-5 semi-final win over seventh-seeded Magdalena Rybarikova. She’ll be vying for a fourth career WTA title.

New Zealand’s Erakovic defeated Stefanie Voegele of Switzerland 6-2 6-4 to earn a shot at a first WTA title. She has two runner-up finishes on her resume, including Memphis last year.