Kimiko Date-Krumm on Friday lauded Kei Nishikori's recent U.S. Open quarterfinal victory over Olympic champion Andy Murray, praising the 26-year-old for showing maturity in the enthralling five-set encounter.
Date-Krumm, 45, reached the women's singles semifinals in three of the four Grand Slams, with the U.S. Open proving her biggest hurdle as she only managed two quarterfinal runs, in 1993 and 1994.
"It was a win that proved he has reached a different dimension, a testament to his growth," the veteran Japanese said of Nishikori.
The former world No. 4 Date-Krumm, who initially retired in 1996 but made a comeback in 2008 at the age of 37 and is currently recovering from knee surgeries before planning to return to the court, said Nishikori's mental fortitude stood out.
"His strength is how well he manages to switch his mindset," she said. "The result (against Murray) came from his ability to alter (his mindset) under any circumstance."
World No. 7 Nishikori will face three-seeded Stan Wawrinka on Friday as he aims to return to the U.S. Open final at Arthur Ashe Stadium.
If he can outduel the Swiss in the semifinal, Nishikori will be out to exorcise some demons in the final to make up for the straight-sets final loss he suffered two years ago against Marin Cilic of Croatia.