Kei Nishikori withstood 15 aces and managed to break Sam Groth's big serve twice for a 6-4, 6-4 victory in the Citi Open quarterfinals Friday.

The second-seeded Nishikori, last year's runner-up at the U.S. Open, saved all four break points he faced en route to reaching a tournament's semifinals for the sixth time this season — and first in five appearances at the hard-court event in Washington.

The first Japanese man to reach a Grand Slam final improved to 41-9 in 2015. Only Novak Djokovic and Andy Murray have won more ATP this matches this year, with 48 apiece.