The world's top two players, Spain's Rafael Nadal and Serbian Novak Djokovic, slumped to a shock loss in their Toronto Masters first round doubles match to a pair of wildcard Canadians. Nadal and Djokovic took the first set 7-5 against the unheralded duo of Vasek Pospisil and Milos Raonic, but then lost the next two sets, 6-3, 10-8. Not since Jimmy Connors was ranked first and Arthur Ashe second when they played together 34 years ago have the top two singles players joined forces in doubles. But the dream doubles team here did not produce the goods, the 20-year-old Pospisil and Raonic, 19, winning the final three games of the second set, and immediately gained control in the match tie-break by rolling out to a 4-0 lead. They earned four match points at 9-5, and after seeing Djokovic and Nadal erase three of those opportunities, finally succeeded in closing out the win in one hour and 34 minutes. Tomas Berdych ousted Sergiy Stakhovsky 6-2, 6-4 Tuesday. In other matches, Serbia's Viktor Troicki upset 11th seed Marin Cilic 6-4, 7-6, while Ukraine's Alexandr Dolgopolov earned a 1-6, 6-2, 7-6 win over Germany's Philipp Petzschner. Italy's Fabio Fognini won 6-2, 6-4 over the Czech Republic's Radek Stepanek in another early match. Argentina's Juan Ignacio Chela beat Alejandro Falla 6-1, 6-3 to set up a daunting second-round match against Roger Federer. In other first-round matches, Canadian Peter Polansky upset No. 13 Jurgen Melzer 7-6 (6), 6-4. Also, No. 12 Mikhail Youzhny beat Frenchman Gilles Simon 6-4, 6-4, Ukraine's Sergiy Stakhovsky defeated Richard Gasquet 7-5, 6-1, Tommy Robredo beat Jarkko Nieminen 6-1, 6-4, Kevin Anderson beat Leonardo Mayer 7-6 (2), 6-4, Julian Benneteau ousted Denis Istomin 6-4, 6-4 and Victor Hanescu beat 19-year-old Canadian wild-card entry Milos Raonic 6-4, 6-4. Karlovic, Ancic pull out Croatians Ivo Karlovic and Mario Ancic have withdrawn from the US Open because of injuries, the US Tennis Association said Monday. Karlovic, a former top-15 player now ranked 63rd, had surgery on his left Achilles' tendon and hasn't played since the Madrid Masters in May. The US Open is the third consecutive Grand Slam tournament he'll miss after entering 26 in a row. Ancic has a back injury and will be skipping a seventh straight major championship. The withdrawals mean that Jamaica's Dustin Brown and Germany's Tobias Kamke move into the main draw. The US Open, the final Grand Slam of the year, starts on Aug. 30 at Flushing Meadows.