Simona Halep said victories by Angelique Kerber at the Australian Open in January and Flavia Pennetta's US Open triumph last September had given the other players the belief that Serena Williams can be beaten.
Flavia Pennetta defeated Roberta Vinci earlier this year in the first ever all-Italian Grand Slam final to claim the biggest win of her career - the US Open, and then announced her retirement from the sport
Flavia Pennetta ended her three-year relationship with former world No. 1 Carlos Moya after he was allegedly found cheating on her with a TV presenter/model.
Flavia Pennetta, who will retire after WTA Finals, stayed on course for her one last title when she beat Poland's Agnieszka Radwanska 7-6, 6-4.
Top seed Simona Halep will be paired in the same group with Maria Sharapova and Flavia Pennetta in the season-ending WTA Finals.
Flavia Pennetta and Angelique Kerber join Simona Halep, Garbine Muguruza, Maria Sharapova, Petra Kvitova and Agnieszka Radwanska in the October 23-November 1 tournament in Singapore.
Flavia Pennetta could hardly find her rhythm facing Lyudmyla Kichenok and the top seed surrendered in one hour and 38 minutes
Apart from Flavia Pennetta, Martina Hingis, Sania Mirza, Kevin Anderson, Marcos Baghdatis are some of the top players who will compete in the Champions Tennis League, to be held from November 23 to December 6.
US Open champion Flavia Pennetta has jumped 18 places to be ranked eighth in the world as the top four remain the same with Serena Williams well clear of second-best Simona Halep.
Flavia Pennetta retired on Saturday only minutes after defeating compatriot and friend-since-childhood Roberta Vinci 7-6 (7/4), 6-2 in US Open 2015 final to become the oldest first-time women's Grand Slam champion.
Far from being despondent after her 7-6 (7/4), 6-2 loss to her childhood friend Flavia Pennetta in the US Open 2015 final, the 32-year-old Roberta Vinci instead showed off a nice line in stand-up comedy.
Flavia Pennetta beat fellow Italian Roberta Vinci 7-6 (7/4), 6-2 in the US Open 2015 final to become the oldest first time women's winner at a major.
The 33-year-old Flavia Pennetta had just become the oldest first-time women's major champion.
Twenty-sixth seed Flavia Pennetta won 7-6, 6-2 to beat unseeded Roberta Vinci in the US Open women's singles final.
Flavia Pennetta and Roberta Vinci's feat of reaching the US Open final knocked everything else, including news related to Sunday's Inter Milan v AC Milan derby off the front page of Italy's most popular sports daily, La Gazzetta dello Sport.
Italy's 43rd-ranked Roberta Vinci and Italy's 26th-ranked Flavia Pennetta will face off in the US Open 2015 women's final.
Flavia Pennetta becomes only the third Italian woman in a Slam final after Francesca Schiavone won the 2010 French Open final and lost in 2011 and Sara Errani, who lost the 2012 French Open final.
US Tennis Association officials postponed the two scheduled women's semi-final matches to Friday due to forecasts of rain on Thursday lasting through the night.