Aug 15 (Reuters) - Twice champion Victoria Azarenka upset Czech 11th seed Barbora Krejcikova 6-3 7-5 on Tuesday to reach the Cincinnati Open second round while Danish wildcard Caroline Wozniacki, in her second tournament out of retirement, lost her opening match. The 34-year-old unseeded Belarusian Azarenka broke Krejcikova four times, saved three of five break points and won the final five games of a match lasting one hour 45 minutes. Krejcikova battled to get the opener back on serve but Azarenka broke right back and then went on to serve out the first set in the following game on her second set point. Former world number one Wozniacki had her chances but failed to convert any of her nine break points while Gracheva's backhand proved too much for the Dane to handle. Czech ninth seed Petra Kvitova, a Cincinnati finalist last year, also booked her spot in the second round with a 7-6(2) 6-0 win over Russian Anna Blinkova.

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Persons: Victoria Azarenka, Caroline Wozniacki, Belarusian Azarenka, Krejcikova, Azarenka, Wozniacki, Varvara Gracheva, Dane, Petra Kvitova, Anna Blinkova, Jelena Ostapenko, Karolina Pliskova, Elena Rybakina, Ukraine's Anhelina Kalinina, Holder Carolina Garcia of, Sloane Stephens, Frank Pingue, Ken Ferris Organizations: Cincinnati, Belarusian, Wimbledon, Court, U.S, Thomson Locations: Czech, Montreal, France, Tunisian, Toronto