SINGAPORE - OCTOBER 26: Naomi Osaka of Japan is comforted by trainer Abdul Sillah after retiring from Women's singles match against Kiki Bertens of the Netherlands during day 6 of the BNP Paribas WTA Finals Singapore presented by SC Global at Singapore Sports Hub on October 26, 2018 in Singapore. (Photo by Clive Brunskill/Getty Images)
SINGAPORE - OCTOBER 26: Naomi Osaka of Japan is comforted by trainer Abdul Sillah after retiring from Women's singles match against Kiki Bertens of the Netherlands during day 6 of the BNP Paribas WTA Finals Singapore presented by SC Global at Singapore Sports Hub on October 26, 2018 in Singapore. (Photo by Clive Brunskill/Getty Images)
SINGAPORE - OCTOBER 27: Sloane Stephens of the United States talks with trainer Abdul Sillah during the break against Karolina Pliskova of the Czech Republic during the women's singles semi final match on Day 7 of the BNP Paribas WTA Finals Singapore presented by SC Global at Singapore Sports Hub on October 27, 2018 in Singapore. (Photo by Matthew Stockman/Getty Images)
SINGAPORE - OCTOBER 26: Naomi Osaka of Japan is comforted by trainer Abdul Sillah after retiring from Women's singles match against Kiki Bertens of the Netherlands during day 6 of the BNP Paribas WTA Finals Singapore presented by SC Global at Singapore Sports Hub on October 26, 2018 in Singapore. (Photo by Matthew Stockman/Getty Images)
