It turns out he was only getting warmed up.

Djokovic upset world No. 1 Roger Federer 7-6 (2), 2-6, 7-6 (2) today to win the $2.45 million Masters Series event, solidifying himself as a serious contender to win the U.S. Open beginning later this month in New York.

"It's a dream come true to win such a strong tournament as this and to win against probably the best player ever in the sport," Djokovic said.

It was third-seeded Djokovic's fourth tournament win this year and his first win in five career matches against Federer, whose 16-match Rogers Cup winning streak ended. The Swiss star won the tournament in 2004 and 2006, and sat out in 2005 with a foot injury.

With wins over Andy Roddick and No. 2 Nadal in his previous rounds, Djokovic also became the first player to beat the world's top three players in the same tournament since Boris Becker defeated No. 3 Michael Stich, No. 1 Pete Sampras and No. 2 Goran Ivanisevic in succession in 1994 in Stockholm.

Federer broke Djokovic to finish off the second set but the Serbian standout broke back to open the third. Federer rallied to tie it at 4.

Djokovic took over in the tiebreaker, finishing off Federer with a drop shot followed by a lob that fell inside the line. Federer's attempted return through his legs struck the net and Djokovic fell to his knees to celebrate.

Djokovic rose from No. 83 into the top 20 last year and has continued to move up this season. He will return this week to the No. 3 ranking, which he first took on July 9 but then surrendered to Roddick.

Federer remains tied with Becker for ninth with 49 career tournament victories.