Washington, DC, USA, 8 August 2015 | AFP

Japan’s Kei Nishikori, last year’s US Open runner-up, has advanced to the semifinals of the Citi¬†Open in Washington DC by beating Australia’s Sam Groth 6-4 6-4.

Fifth-ranked Nishikori, the highest¬†remaining seed after Britain’s Andy Murray crashed out in his opening match, booked a Saturday semifinal meeting with the Croatian that beat him in the US Open decider, Marin Cilic.

Cilic accounted for German teen Alexander Zverev.

Nishikori seeks his third title of the year after Memphis and Barcelona and the 10th of his career. The 25-year-old Asian No.1 has reached his seventh ATP semifinal of the year.

Nishikori took advantage of his fifth break chance of the seventh game, taking a 4-3 lead when the Aussie hit a forehand drop volley wide, and held twice more to take the first set in 39 minutes.

Groth, ranked a career-best 62nd this week, denied Nishikori on three break points to hold in the opening game of the second set, but Groth’s fourth double fault of the match later gifted Nishikori a break for a 3-2 edge.

Nishikori denied Groth on two break points in the eighth game, holding for a 5-3 lead, and held at love in the final game to conclude matters after 86 minutes.

Groth, whose only ATP semifinal was last year at Newport, fired 15 aces but fell to 0-4 against top-10 foes in dropping his first meeting with Nishikori.

The semifinal showdown will be the first match since Cilic downed Nishikori 6-3 6-3 6-3 at Arthur Ashe Stadium last September for his first Grand Slam crown.

“It’s going to be great motivation for me,” Nishikori said. “I think it’s going to be very interesting.”

Nishikori, who has a 5-3 edge on Cilic in their all-time rivalry, said he recalls not being at his best for the biggest moment of his career thus far and welcomes another chance at the man who frustrated his dream.

“I was really nervous and I wasn’t really into the match,” Nishikori said. “Physically I wasn’t 100 per cent.

“I’m a better player than last year. I’m a little more solid baseline player. I’m a more aggressive player than before. I think I’m getting better. It’s going to be a good match tomorrow.”