BEIJING (AP) — Two days after announcing the end of her momentous tennis career in an open letter to friends and fans, Li Na entered her farewell news conference with the appearance of somebody who had been crying. It didn't take long for the two-time Grand Slam champion to shed tears, again, as she explained her decision to retire in the wake of a fourth knee operation. "I feel this is the best time for me to retire.Read more on NewsOK.com