Melbourne - Italian top seeds Sara Errani and Roberta Vinci ousted Venus Williams and her hobbling sister Serena in the Australian Open women's doubles quarter-finals on Tuesday.
The Williams sisters were the heavy favourites to win the event, despite being seeded 12th because of their sporadic appearances in doubles on tour.
They made a dominant start but Serena, who appeared to aggravate an ankle injury sustained in her first singles match, and was seen limping and grimacing, failed to take her chance to serve out the match in the second set.
Venus lost her serve in the 11th game of the final set and the Italians closed out a 3-6, 7-6 (7/1), 7-5 victory that put them into a semi-final against Russia's No 4 seeds Ekaterina Makarova and Elena Vesnina.
The Australian duo of Ashleigh Barty and Casey Dellacqua defeated Russia's Anastasia Pavlyunchenkova and Czech Lucie Safarova 6-2, 6-3 to move into the semi-finals against Varvara Lepchenko and China's Saisai Zheng.
In the men's doubles, the top-seeded American duo of Bob and Mike Bryan will play their quarter-final on Wednesday against Italy's Daniele Braccali and Czech Lukas Dlouhy.
Two pairings are already through to the semi-finals: Spaniards Marcel Granollers and Marc Lopez, the third seeds, will face the Dutch duo Robin Haase and Igor Sijsling on Thursday.