World number one Rafael Nadal tamed the big-serving American John Isner 6-4, 7-6 (7/0) to surge into the semifinals of the China Open on Friday.

The brilliant Spaniard, on course for a sixth title this season, faces Bulgaria's third seed Grigor Dimitrov in the last four on Beijing's outdoor hard courts.

The 31-year-old Nadal described Isner's serve as "huge" on the eve of their quarterfinal blockbuster.

And Nadal came under the expected barrage before he grabbed the crucial break of serve in the ninth game of a tight first set.

Isner, seeded sixth, blasted 11 aces in the opening set but Nadal punished him at the first sniff of an opportunity.

The second set was even tighter, until Nadal stepped up another gear in the tie break.

Nick Kyrgios also advanced. The eighth-seeded Australian won when opponent Steve Darcis retired from the match with a neck strain while trailing 6-0, 3-0.

Kyrgios will next face second-seeded Alexander Zverev. The 20-year-old German beat Andrey Rublev 6-2, 6-3 and qualified for the season-ending tournament in London.

Earlier, second-seeded Simona Halep reached the semifinals by beating Daria Kasatkina 6-2, 6-1.

The Romanian could take over the top ranking from Garbine Muguruza. She needs to reach the final and not lose to third-seeded Elena Svitolina.

Halep will next face either ninth-seeded Jelena Ostapenko or Sorana Cirstea.

Petra Kvitova advanced by beating Barbora Strycova 6-3, 6-4. The 12th-seeded Kvitova will next face either Svitolina or Caroline Garcia in the semifinals.

Source: Khaleej Times