Tennis-Serena retires injured in Toronto final against Andreescu

Serena Williams' first U.S. Open tune-up ended in stunning fashion as the American retired with an injury while trailing Canadian teenager Bianca Andreescu 2-1 in the Rogers Cup final on Sunday.

Williams, who hopes to chase a record-equalling 24th career Grand Slam title at the U.S. Open, seemed fine on the court but suddenly sat crying in her chair before deciding to retire 19 minutes into the match with a back injury.