Russian third seed Maria Sharapova withdrew from the US Open with a right

leg injury, easing the path to a calendar-year Grand Slam for top-ranked Serena Williams.

US Open tournament director David Brewer announced Sharapova's exit, which allowed qualifying

lucky loser Daria Kasatkina of Russia into the draw in Sharapova's place.

Sharapova had been the highest-seeded rival in Williams' half of the US Open draw, a status

that now belongs to seventh-seeded Serbian Ana Ivanovic, a possible semi-final foe for

Williams.

Williams is trying to complete the first Grand Slam calendar-year title sweep since Steffi

Graf in 1988 and match Graf's Open Era-record of 22 Slam singles crowns.