In an interview to Fanatik, Serena Williams's coach Patrick Mouratoglou recalled the American player's three-set loss to Roberta Vinci in the 2015 US Open semifinal. At that stage of the tournament, Serena was a strong favorite to win the trophy and achieve the Calendar Grand Slam.
Instead the Italian surprisingly beat her to set a final against her compatriot Flavia Pennetta. "For Serena that time was extremely tough", said Mouratoglou, who has been working with Williams since June 2012. "She had won four consecutive Grand Slams and lost in the semifinals on the fifth.
She felt she had broken everything she had done in the past. She felt so much disappointed like if she had not won any of the four previous Slams! That hit her so bad. And this is one of the reasons why she lost the Australian Open finals against Angelique Kerber or against Garbine Muguruza at the French Open.
She suffered a lot. And when you suffer, sometimes you do not think in such a clear way about how you did before. It took time to get back." That season, in 2015, Serena ended her season in Flushing Meadows as she withdrew from the WTA Finals due to an injury. She last played the women's championship tournament in Singapore in 2014.