Defending champion Serena Williams has overpowered fellow-American Sloane Stephens 6-4 6-1 to reach the quarter-finals of the U.S. tennis Open in New York.
Top-seeded Williams avenged a defeat to Stephens in the quarter-finals of this year's Australian Open with a display of power tennis.
31-year-old Williams is trying to become the oldest women's U.S. Open champion since tennis turned professional in 1968, and is chasing her 17th grand slam title.
She'll meet 18th seed Carla Suarez Navarro in the quarter-finals, after the Spaniard upset eighth-seeded Angelique Kerber of Germany.
