US Open 2015: Williams sisters on collision course; Djokovic reaches quarters

World no 1 Serena Williams was in sublime form on Sunday, 6 August, as she easily disposed off compatriot Madison Keys in straight sets to reach the women's singles quarter-finals at Flushing Meadows.

Serena overcame hard-hitting Keys 6-3, 6-3 to set up a last-eight encounter against her sister Venus, who cruised to a comfortable 6-2, 6-1 win over Estonia's Anett Kontaveit.

With Sunday's win, Serena stands only three wins away from securing the first calendar Grand Slam since Steffi Graf in 1988.

Meanwhile, in the men's singles category, Novak Djokovic overcame Spaniard Roberto Bautista Agut in four sets, 6-3, 4-6, 6-4, 6-3, to reach his 26th consecutive quarter-final at a Grand Slam.

The Serbian will next face Feliciano Lopez, who defeated Rafael Nadal's conqueror Fabio Fognini in the 4th round, 6-3, 7-6 (5), 6-1.

Defending champion Marin Cilic too advanced to the quarters with a 6-3, 2-6, 7-6 (2), 6-1 win over Frenchman Jeremy Chardy.

(With inputs from ANI)