Tennis: Karolina Pliskova wins twice to reach semis in Cincinnati, closes in on cementing No. 1 spot

Karolina Pliskova (CZE) returns a shot against Caroline Wozniacki (DEN) during the Western and Southern Open at the Lindner Family Tennis Center on Aug 18, 2017.
Karolina Pliskova (CZE) returns a shot against Caroline Wozniacki (DEN) during the Western and Southern Open at the Lindner Family Tennis Center on Aug 18, 2017.PHOTO: REUTERS
Simona Halep (ROU) returns a shot against Johanna Konta (GBR) during the Western and Southern Open at the Lindner Family Tennis Center on Aug 18, 2017.
Simona Halep (ROU) returns a shot against Johanna Konta (GBR) during the Western and Southern Open at the Lindner Family Tennis Center on Aug 18, 2017.PHOTO: REUTERS

Cincinnati, Ohio (AFP) - Defending champion Karolina Pliskova won twice in one day for the third time this season, tightening her grip on the world No. 1 ranking on Friday to reach the WTA Cincinnati Open semi-finals.

The 25-year-old Czech, fighting to hold off Romania's Simona Halep atop the rankings, first ousted Italian qualifier Camila Giorgi 6-3, 4-6, 6-0 in one of five matches postponed from Thursday due to rain.

With only two hours between matches, Pliskova defeated Denmark's fifth-ranked Caroline Wozniacki 6-2, 6-4 to book a Saturday semi-final against Wimbledon champion Garbine Muguruza.

"I feel pretty good," Pliskova said. "I recover well, so definitely I will be ready for tomorrow."

The only one of four rivals who could have toppled Pliskova this week still with hope is second-ranked Halep, who ripped British seventh seed Johanna Konta 6-4, 7-6 (7-1) to book a semi-final date with US wildcard Sloane Stephens.

"Whatever comes I will just take it," said Pliskova. "Even if I would be second coming to the US Open, it's still better than I was last year. So no pressure about being world No. 1."

Pliskova's two-in-one effort, matching feats on her way to Eastbourne and Doha titles, means Halep must capture the crown to swipe the top spot in Monday's rankings.

Ukraine's fourth-ranked Elina Svitolina lost her chance at No. 1 when she fell 7-5, 6-4 to Germany's Julia Gorges, who then lost to Stephens 6-1, 7-6 (7-3).