Caroline Wozniacki of Denmark blows a kiss after defeating Aliaksandra Sasnovich of Belarus during their match at the 2014 U.S. Open tennis tournament in New York, August 27, 2014. REUTERS/Mike Segar
#10 Caroline Wozniacki Total earnings: $10.8 million Prize money: $1.3 million Endorsements: $9.5 million REUTERS

Former world no. 1 Caroline Wozniacki posts a selfie on Instagram while training for the upcoming New York City Marathon at the Central Park. Although the 24-year-old plays a full tournament schedule this fall, she still manages to squeeze time to train for the New York City Marathon and cover 26.2 miles. She usually runs 30-40 minutes a day as part of her tennis training routine, but she adds longer running sessions every week to prepare for the marathon on November 2.

Wozniacki, who revealed that 10K was her longest run so far, is not seeking this challenge to distract herself from her recent breakup with the professional golfer and world no. 1 Rory McIlroy. Back in May, Wozniacki decided to join the marathon less than a month after McIlroy broke off their engagement.

"Tennis helped me just get through the tough times," Wozniacki said according to ESPN. "Now I'm just feeling happy and I wanted to do something good for others."

The 24-year-old Wozniacki will run the New York City Marathon to raise funds for the New York Road Runners Team for Kids charity to promote youth running. Meb Keflezighi, last year's Boston Marathon winner, will also raise money for the program at this year's New York City Marathon.

Wozniacki has remained mum about her goal marathon time. Back in July, she claimed that her main goal is to finish the race, joking that she'll crawl toward the finish line if she has to.

Meanwhile, Wozniacki was defeated by Ana Ivanovic and secured her fourth WTA title on Sunday at the Pan Pacific Open 6-2, 7-6(2). In a match between the two former world no. 1s, the Serbian broke the Dane three times during the first set at the Ariake Coliseum in Japan and took the second-set tie-break with a forehand to the corner.