Greece's Maria Sakkari delivered one of the biggest upsets of her career at the WTA San Jose tournament on Friday, ousting former seven-time Grand Slam champion Venus Williams in a straight sets shocker.

Sakkari, 23, saved two set points in the second set en route to a 6-4, 7-6 (7/2) victory over the former world number one, punching her ticket to the semi-finals where she will face another unseeded player, Danielle Collins. World No.49 Sakkari needed an hour and 43 minutes to dispatch Venus, who rolled through her first three matches without dropping a set.