Tennis News &  Rumors - Serena Williams started her WTA Championship defense on a winning note, as she dispatched Serbian darling Ana Ivanovic 6-4, 6-4 in the first of three matches in the round-robin stage.

Of course, her coach and rumored boyfriend Patrick Mouratoglou is more than delighted to see Serena dominating again, pumping fist to show support to the reigning world's no.1 netter.

It has been an up-and-down year for Williams after dealing with early-round exits in the first three Grand Slams (Australian, French and Wimbledon Open) and myriad of injuries (knees and stomach virus). However, Serena keeps on finding ways to win despite all of kinds of circumstances.

In an interview with the New York Times a month ago, Mouratoglou believed Williams' slight drop off this season may perhaps stem from her lack of confidence and motivation to win after a dominant performance in 2013, when she bagged the French and US Open championships along with her fourth WTA Finals title.

"It's difficult to understand," Mouratoglou told the New York Times. "The only explanation we have is that after the year and a half she spent winning so much and playing so much, she had a moment where she dropped a bit in terms of her nerves and her mental game and then lost matches. In the losing matches, she lost a bit of confidence."

Although there were rumors about a rift between him and Williams, the French tennis coach downplayed the report and claimed that Serena would somehow find her old groove back after these adversities.

And apparently, he was right again as Williams went on to claim the US Open Championship for the third straight time and sixth time overall and then last week surpassed Martina Hingis for the fourth place in the list of longest reigning world's no.1 in WTA history.

The 33-years old Williams will continue her campaign on Tuesday against Canadian rising star Genie Bouchard, who lost her opening Red Group match to Simona Halep 2-6, 3-6 on Sunday at the Singapore Indoor Stadium.