Nishikori stuns Murray, Serena advances

New York: Japan's Kei Nishikori overcame second seed Andy Murray for a gruelling 1-6, 6-4, 4-6, 6-1, 7-5 see-saw victory on Wednesday to reach the US Open semifinals. Nishikori, who became the first Asian man to reach a grand slam final when he finished runner-up here in 2014, broke the Scotsman in the 11th game of the fifth set with a brilliant reflex volley and served out to complete the triumph.

The upset ended a stellar run by Murray that had taken him to seven successive finals, including victories at Wimbledon, the Rio Olympics, Queen's Club and Rome. “It was too exciting on the court, but I tried to stay calm,” Nishikori said in an on-court interview. “It was really tough to stay calm. There were many ups and downs.”“In the end it was great tennis, so very happy.”

The 26-year-old will now face third seed Stan Wawrinka, who beat 2009 champion Juan Martin del Potro 7-6(5), 4-6, 6-3, 6-2. The Swiss, who hit 53 winners including 10 aces here on Wednesday. The late night match was a contrast in styles between Wawrinka's balanced attack and del Potro's forehand-centric game.

Played in humid conditions, the Argentine raced to a 3-0 lead in the first set, but Wawrinka's precise baseline patterns and finishing power from the backhand side allowed him to regain the initiative. Wawrinka started the fourth set with a break and held his nerve to record his 37th match win of the season (37-12 overall). It was his first victory over del Potro since 2008 Wimbledon.

Wawrinka has a 3-2 advantage over Nishikori in their head to head record. Meanwhile, World No1 Serena Williams, seeking a record seventh US Open title and 23rd Grand Slam crown, fired 18 aces en route to the triumph on Wednesday night, which set up a meeting with first-time Grand Slam semi-finalist Karolina Pliskova for a place in Saturday's championship match.

But she made her task against the 2014 French Open finalist harder with 43 unforced errors and Halep, firing on all cylinders from the baseline took advantage. The Romanian became the first player in the tournament to break Williams's serve, and the first to take a set off the top seed. But after failing to convert any of a dozen break points in the second set, Williams regained control in the third with a break for 3-1 and steamed home from there.

“I knew I could play a lot better,” Williams said of her frustration in a second set that lasted 65 minutes. “She kept going for her shots she stepped it up.” Williams's semifinal against Pliskova promises more fireworks. The 10th-seeded Czech leads the WTA tour in aces this year. After surviving a match point en route to a fourth-round victory over Venus Williams, Pliskova beat 18-year-old Croatian Ana Konjuh 6-2, 6-2.

“I'm so excited to be in my first semifinal,” said Pliskova, who had failed to make it out of the third round in 17 prior Grand Slam appearances. Despite her dearth of Grand Slam success, Pliskova is playing with confidence after winning her biggest title to date on the hard courts of Cincinnati.

She beat Angelique Kerber in the final to deny the German world number two's bid to supplant Serena atop the world rankings. Kerber, who booked her semifinal slot on Tuesday with a 7-5, 6-0 victory over 2015 finalist Roberta Vinci, can still nudge Serena from the summit.