LOS ANGELES: Three-time defending champion Kei Nishikori and Japanese compatriot Yoshihito Nishioka, a 130th-ranked qualifier, advanced to the quarterfinals of the ATP Memphis Open on Wednesday with straight-sets triumphs.

Top seed Nishikori defeated 124th-ranked Ryan Harrison 6-2, 7-5 to book a last-eight date against Kazakstan’s Mikhail Kukushkin in the indoor hardcourt tournament.

Seventh-ranked Nishikori beat the American in the second round at Memphis for the second year in a row. Nishikori also won their only other prior meeting last year at Indian Wells.

Nishikori served for the match in the 10th game of the second set but Harrison denied him on four match points and forced the first break points the Asian star faced in the match, finally cracking his serve on his fifth chance to level the set at 5-5.

Nishikori responded by breaking Harrison again in the next game and holding at love to claim the victory after 81 minutes.

Left-hander Nishioka downed Ukraine’s Illya Marchenko 6-1, 6-3 to book a quarterfinal match against US fourth seed Sam Querrey, who eliminated Swiss qualifier Henri Laaksonen 6-3, 6-4.

Kukushkin advanced by ousting US fifth seed Denis Kudla 6-1, 7-5, winning 22 of 30 points off the American’s second serve.

Troicki meet Mahut

In Rotterdam, eighth-seeded Viktor Troicki made the quarterfinals of the World Tennis Tournament by defeating Hyeon Chung of South Korea 7-6 (5), 6-2 on Thursday.

Troicki, runner-up in Sofia last weekend, will take on French qualifier Nicolas Mahut for a place in the semifinals.

Mahut saved all seven break points he faced, and broke big-serving Jeremy Chardy once to post a 7-5, 6-2 win in an all-French match at the indoor tournament.

“I was just focused on holding serve and I’m happy to go through,” Mahut said. “I feel great, but I know it’s going to be tough against Troicki, who I lost to in the Sydney quarterfinals.”

Erratic Venus in quarters

Venus Williams beat Poland’s Urszula Radwanska 6-4, 6-2 to set up a Taiwan Open quarterfinal against Anastasija Sevastova, despite not hitting top form on Thursday.

The top seed was broken in each set but she still had too much for Radwanska, ranked 101 places lower at 113th in the world, as she went through in 86 minutes.

The seven-time Grand Slam winner, 35, sent down two double faults and only landed 48 percent of her first serves in the first set but reached her debut quarter-final of 2016.

Next up for Williams is a first career meeting with Latvia’s Sevastova, also ranked outside the top 100 at 103, as she eyes her 49th tournament victory.

Local hope Hsieh Su-wei beat Mandy Minella 6-4, 4-6, 6-2 to join Williams in the last eight alongside fellow seed Misaki Doi of Japan, who ousted Magda Linette 6-2, 6-3.