UPDATE 1-Tennis-Serena Williams retires from Indiana Wells match

Serena Williams retired from the BNP Paribas Open while trailing Spain's Garbine Muguruza 6-3 1-0 at Indian Wells on Sunday.

The former world number one walked to the chair after the first game of the second set and sat down, breathing heavily. After a discussion with supervisor Donna Kelso, the American retired. Williams, 37, had shown signs of fatigue during the first set and after it was completed she called for a trainer and following a lengthy conversation returned to the court.

She retired after losing the first game. Williams had taken a 3-0 lead in the first set before losing the next seven games.

Williams, who has won 23 Grand Slam singles titles, gave birth to a daughter in 2017 and returned to play last year. She is currently ranked 10th in the world. (Reporting by Gene Cherry in Raleigh, North Carolina; Editing by Ken Ferris)