Olympic champion and world number one Serena Williams tumbled out of the Rio de Janeiro singles competition in the third round on Tuesday (August 9) after a shock defeat to Ukraine's Elina Svitolina. <br /> <br />Svitolina, who is ranked 20th in the world, stunned the London Games gold medallist 6-4 6-3 to record a memorable victory against the American, who has won 22 grand slam singles titles. <br /> <br />Svitolina will face Czech Republic's Petra Kvitova in the quarter finals. <br /> <br />Williams was visibly frustrated throughout the match as she struggling to find her range, making 37 unforced errors compared to 17 by Svitolina. <br /> <br />Late in the second set, Williams served five double faults in a single game, which drew gasps from a shocked audience. <br /> <br />Williams, who has won three women's doubles Olympic titles with sister Venus, was also eliminated with her sister from the doubles on Sunday.