TOKYO (Reuters) - Local wildcard Tatsuma Ito claimed the biggest win of his career when he ousted top seed and world number four Stan Wawrinka 7-5 6-2 in the first round of the Japan Open on Tuesday.
The world number 103 sealed the stunning victory on his second match point, blasting a backhand volley into an open court after his wide serve had forced Wawrinka out of position.
The Australian Open winner struggled throughout the contest at the ATP 500 event, dropping serve four times and hitting 25 unforced errors in his first tour event since losing to Ito's compatriot Kei Nishikori at the U.S. Open earlier this month.
Wawrinka, who helped Switzerland reach the final of the Davis Cup two weeks ago, lost his serve in the third game on the Tokyo hard court, only to break back and hold for a 5-4 lead in the first set.
However, the 29-year-old failed to take advantage as the Japanese, who has never made an ATP final and had only two previous wins on tour this year, took the set and an early lead in the second with a run of five straight games.
Wawrinka threatened a break back at 3-2 down but the busy Ito, wearing his baseball cap back to front, survived the scare and broke the Swiss once again as he confidently finished off the match against a dejected opponent.
The loss delays Wawrinka's bid to qualify for the season-ending ATP World Tour Finals in London, which the Swiss could have achieved had he reached the final in Tokyo.
He is fourth in the race for one of the eight spots available at the November event.
Ito, 26, has no hope of making it to London but will instead look forward to a second round clash against German Benjamin Becker, who advanced after Finn Jarkko Nieminen retired from their match through fatigue when trailing 7-5 4-1.
Sixth seed Roberto Bautista Agut also failed to go the distance in his match, the Spaniard pulling out with a thigh injury after blowing six match points against Gilles Simon of France.
Simon led 4-6 7-6(7) 2-1 when his opponent called it a day.
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THE RACE TO LONDON:
1 Novak Djokovic 8150-qualified
2 Roger Federer 7020-qualified
3 Rafa Nadal 6645-qualified
4 Stan Wawrinka 4795
5 Marin Cilic 3935
6 Kei Nishikori 3845
7 David Ferrer 3535
8 Tomas Berdych 3510
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9 Milos Raonic 3440
10 Andy Murray 3405
11 Grigor Dimitrov 3360
12 Jo-Wilfried Tsonga 2650
13 Ernests Gulbis 2445
(Writing by Patrick Johnston in Singapore; Editing by John O'Brien)