Exactly 11 months after meeting in the U.S. Open final, Marin Cilic and Kei Nishikori will face each other again on a hard court. This time, it'll be in today's semifinals of the Citi Open, a tuneup event for the year's last Grand Slam tournament. Reigning U.S. Open champion Cilic moved into the final four in Washington for the first time since 2010 by beating 18-year-old Alexander Zverev, 7-5, 7-6 (3), on Friday. Earlier, the second-seeded Nishikori withstood 15 aces and managed to break Sam Groth's big serve twice for a 6-4, 6-4 victory. On Sept. 8, 2014, Cilic beat Nishikori in straight sets at Flushing Meadows, the only Grand Slam title match for either. They have not played each other since. "Emotions-wise, it's going to be completely different. For the Slam final, we were both pretty nervous," the third-seeded Cilic said. "I'm going to, for sure, take out some things, some critical things, that were working for me to be able to get the win." Said Nishikori: "For me, it's great motivation to play Marin." "I'm sure that I am a better player than last year," added Nishikori, the only Japanese man to participate in a major final. "I think I have more patience and [am] a more solid baseline player and I try to be a little more aggressive than before." This the first time the Citi Open field included both men's finalists from the previous year's U.S. Open. "Win or lose," Cilic said, "it's going to give me a lot of feedback for my game." On the other half of the draw, eighth-seeded John Isner — twice the runner-up in Washington — delivered 20 aces and defeated Ricardas Berankis of Lithuania, 6-3, 5-7, 6-3. In an all-U.S. semifinal, Isner will face 55th-ranked Steve Johnson, who beat yet another American, 15th-seeded Jack Sock, 7-6 (5), 6-1 in Friday's last match. In the women's quarterfinals, 2011 U.S. Open champion Sam Stosur advanced when Monica Niculescu stopped playing because of a left abdominal strain while trailing 4-0. Stosur faces Sloane Stephens today. Stephens picked up a 6-4, 6-4 victory over 19-year-old wild-card entry Louisa Chirico. The other women's semifinal will be No. 1-seeded Ekaterina Makarova against Anastasia Pavlyuchenkova. Makarova beat No. 6 Irina-Camelia Begu, 6-4, 2-6, 6-1, while Pavlyuchenkova edged Christina McHale, 2-6, 6-1, 7-6 (5).