World No. 3 Caroline Wozniacki enjoyed the biggest win of her career on Sunday when she upset American Venus Williams 6-4, 6-4 in the WTA Finals in Singapore. Wozniacki had lost all her previous seven matches against Williams, who was trying to win her first WTA Finals since 2008.

The Dane finished the match with a signature backhand down the line on second match point before erupting in joy. It was the 27-year-old Wozniacki's best result at the WTA Finals since reaching the 2010 final in Doha, Qatar. Since then, Wozniacki underwent several serious injuries and nearly contemplated retirement. However, she has bounced back stronger than ever in 2017, winning 60 matches in the season.

After the win, Wozniacki exclaimed that eight was her lucky number. "Eight is my lucky number, so I was hoping if I was going to beat her (Williams) at least once in my career it would be today. I just went out there and did my best," she said at the presentation ceremony.

Caroline Wozniacki clinches biggest win of career

Woznicki escaped a shaky first set when she dropped a service game after claiming a 5-3 lead. "I'm still shaking. I was up 5-0 and then Venus started upping her game. She went for her shots, started serving into my body. I'm just so happy I managed to win in the end."

Williams was in pursuit of her 50th career WTA title, on the same day Roger Federer surpassed Ivan Lendl on the all-time list with his 95th ATP title. Williams, despite starting the year with a finals appearance at the Australian Open, hadn't won a single WTA title entering the Finals. In fact, she was the only participant without a title. She had also reached the final of the Wimbledon where she lost to Spain's Garbine Muguruza.

"I didn't seem to come up with my best tennis until it was too late. I'll try to play a little better earlier next time. That might be a good plan," Williams said, looking forward to the 2018 WTA season.