NEW DELHI, Jan. 17 -- The forehand flew just long. "Out," called Karteek Reddy, a rising young tennis player, rallying with Sania Mirza on a recent Friday afternoon in Hyderabad. On the other side of the net, Mirza, in a blue T-shirt, dark blue tights and bun spilling out of her black cap, squinted and defied the call, hands on hips. "You mean out of reach, baby!" she said, laughing.

Mirza's forehand has indeed been a formidable stroke, out of reach of her opponents, from the beginning of her career, a weapon that has propelled her to six Grand Slam doubles titles, a clutch of Asian Games gold medals, and the No.1 doubles ranking in 2015. But it has not been in competitive action since she took an injury break in October 2017, and sat out ...