Del Potro, Raonic advance; Nishikori out in Tokyo

Tokyo, Japan ( - Juan Martin del Potro and Milos Raonic were among the quarterfinal winners Friday at the Japan Open Tennis Championships, but defending champion Kei Nishikori was eliminated by Nicolas Almagro.

The top-seeded del Potro rallied for a 4-6, 6-4, 6-2 win over Alexandr Dolgopolov of the Ukraine and will next meet the sixth-seeded Almagro, who took out last year's champ with a 7-6 (7-2), 5-7, 6-3 victory.

Del Potro improved to 5-0 lifetime against Dolgopolov and is in position to reach the final in Tokyo for the second time. The Argentine star was the 2008 runner-up to Tomas Berdych.

Another win would also put del Potro into his fourth final of 2013. He won in Rotterdam and Washington, while falling to Rafael Nadal in Indian Wells.

Almagro, who won the final three games of his match against Nishikori, has reached a pair of finals this year and lost both. The Spaniard fell to John Isner in Houston and Nadal in Barcelona.

The third-seeded Raonic continued his strong play of late with a 6-3, 6-3 rout of Slovakian lucky loser Lukas Lacko. The Canadian won the Thailand Open crown last weekend and is bidding to reach the final at this event for the second straight year. He lost to Nishikori in three sets last year.

Next up for Raonic will be Croatia's Ivan Dodig, a 6-2, 7-6 (7-3) winner over Finland's Jarkko Nieminen. Dodig knocked off second-seeded Jo-Wilfried Tsonga in the second round.