Angelique Kerber’s tennis career came to an end when the former world number one and three-time grand slam champion lost 6-7 (4-7), 6-4, 7-6 (8-6) against Zheng Qinwen in the Paris Olympics quarter-finals on Wednesday. The sixth seeded Australian Open runner-up Zheng prevailed in a concluding tie-break after 3 hours 4 minutes, coming back from 4-1 down in the final set, and after losing the first set from 5-3 up at the French Open venue of Roland Garros. German Kerber showed her famous fighting spirit one final time when she rallied from 6-3 down to 6-6 in the final tie-break, before finally h…