( CNN ) -- She had nightmares about taking part in the New York City Marathon -- in one she even dreamed she was dead prior to getting to the start line -- but it turns out Caroline Wozniacki need not have worried . For one the tennis ace from Denmark completed the grueling 26.2-mile journey Sunday , which was impressive enough given only about a week ago did Wozniacki 's lengthy season come to an end in Asia . Secondly the former world No . 1 posted a time of just over three hours and 26 minutes . Wozniacki tweeted the secret to her finishing was `` carb loading , '' posting a picture of herself munching mountains of popcorn , while watching the New York Rangers play ice hockey against the Winnipeg Jets with friend Serena Williams on Saturday . Waiting for her at the finish line was Williams , who just happened to beat Wozniacki in the U.S. Open final in New York two months ago . `` I never tried anything this hard , '' Wozniacki was quoted as saying by the New York Daily News . `` This is the toughest physical challenge ever . `` You have to keep going , keep going . I just kept grinding out there . '' It was always on Wozniacki 's `` bucket list '' to run the marathon and she raised funds for the charity Team for Kids . Despite Wozniacki 's athletic background , the race did n't go down without a hitch . She hit a wall , said the Daily News , at the 20-mile mark . But the 24-year-old -- formerly engaged to golf No . 1 Rory McIlroy -- ended strongly and was congratulated by Williams . Her feat also drew praise from fellow players and retired greats such as Billie Jean King . Wozniacki said completing the marathon would help her tennis game . `` I know I can be out there for hours and be fine , '' she was quoted as saying by the Daily News . `` I can keep battling it out there and I think that 's a great mental advantage to have when you go out to play . '' Presumably , though , she 'll take a break first .
Caroline Wozniacki completes the Denmark Marathon in just over three hours , just over three hours . She was met at the finish line by one of her best pals , fellow tennis player Wozniacki . Wozniacki ran for charity after saying it was on her `` bucket list '' to take part in the race . Serena Williams was formerly engaged to the world 's top-ranked golfer , Rory McIlroy .