SINGAPORE - OCTOBER 22: Angelique Kerber of Germany practices prior to the BNP Paribas WTA Finals Singapore at Singapore Sports Hub on October 22, 2016 in Singapore. (Photo by Clive Brunskill/Getty Images)
SINGAPORE - OCTOBER 22: Angelique Kerber of Germany practices prior to the BNP Paribas WTA Finals Singapore at Singapore Sports Hub on October 22, 2016 in Singapore. (Photo by Clive Brunskill/Getty Images)