INDIAN WELLS, CA - MARCH 14: Angelique Kerber of Germany walks off the court after her straight set defeat by Elena Vesnina of Russia in their fourth round match during day nine of the BNP Paribas Open at Indian Wells Tennis Garden on March 14, 2017 in Indian Wells, California. (Photo by Clive Brunskill/Getty Images)

INDIAN WELLS, CA - MARCH 14:  Angelique Kerber of Germany walks off the court after her straight set defeat by Elena Vesnina of Russia in their fourth round match during day nine of the BNP Paribas Open at Indian Wells Tennis Garden on March 14, 2017 in Indian Wells, California.  (Photo by Clive Brunskill/Getty Images)