Voskoboeva is a qualifier in Toronto and entering Thursday's action she had already overachieved with wins over both Marion Bartoli and Flavia Pennetta.
However, making the third round wasn't 'good enough' for the player from Kazahkstan, and she booked her spot in the quarterfinal round of the Premier Mandatory event. She will next face Victoria Azarenka of Belarus and if she can survive that contest, she might face Serena Williams in the semifinals.
Voskoboeva is playing the best tennis of her career in Toronto, and after starting the WTA season as a player outside of the top 500, she's clearly demonstrating that she can compete with the best players on tour.
She almost had a meltdown against Sharapova on Thursday after squandering three match points in the second set, all of which were on her serve. Two of those missed match points were on double faults.
However she managed to recover later in the set for the 6-3, 7-5 victory.
Sharapova is not the only seeded player to fall on Thursday, as Wimbledon champion Petra Kvitova lost to Andrea Petkovic.
French Open champion Na Li has also been eliminated as she suffered a setback to Australia's Sam Stosur.