Nicolas Almagro, Juan Martin del Potro among Japan Open semifinalists Nicolas Almagro, shown at this year's French Open, on Friday defeated defending champion Kei Nishikori and advanced to the semifinals of the Japan Open. TOKYO, Oct. 4 (UPI) -- Nicolas Almagro defeated defending champion Kei Nishikori in three sets Friday in the quarterfinals of the ATP's Rakuten Japan Open. Almagro, the No. 6 seed, took out the fourth-seeded Nishikori 7-6 (7-2), 5-7, 6-3. He was able to finish off five of his six break opportunities, including both chances he had in the third set. Nishikori had a pair of breaks in each the first and second sets but Almagro lost only five points over four service games in the third set to gain a spot in the semifinals. Almagro will next play No. 1-seeded Juan Martin del Potro, who came away a 4-6, 6-4, 6-2 winner over Alexandr Dolgopolov. Del Potro had his serve broken three times in losing the first set before winning nearly two-thirds of the points on serve the rest of the way. Del Potro, who also came from behind to beat Dolgopolov earlier this year, is 5-0 in his career versus the Ukrainian. Third-seeded Milos Raonic, who lost to Nishikori in last year's Japan Open final, defeated Lukas Lacko 6-3, 6-3 in 62 minutes, losing 10 points in nine games serving. Ivan Dodig got past Jarkko Nieminen 6-2, 7-6 (7-3) in the fourth quarterfinal. Saturday's semifinals will mark the first career meeting between del Potro and Almagro. Dodig won both times he played Raonic.