Serena Williams turned back the clock on Wednesday to stun world number two Anett Kontaveit 7-6(4), 2-6, 6-2 and move into the third round of the U.S. Open, putting her retirement plans on pause. Defeat has always been hard to swallow for the fiercely competitive Williams and the 40-year-old American's relentless will to win was on full display during an absorbing two-hour 27 minute contest of unexpected high quality, breathless intensity and drama. Williams had signalled her intention to retire earlier this month, saying she was "evolving away from tennis" but never confirming the U.S. Open as her final event.