Number two Rafael Nadal and third-ranked Novak Djokovic are smelling blood, less than 24 hours after Roger Federer's untimely second-round ouster at the ATP Toronto Masters Series event.

The pursuing pair - Nadal in the runaway lead between them - are moving toward a possible changing of the guard at the top of tennis after 234 weeks of the Swiss reign.

Djokovic staked his continuing claim, coming back after a Wimbledon second-round elimination, to reach the quarter-finals with a defeat of Swede Robin Soderling 6-4, 6-4.

Nadal, due to play his third-round match against Russian Igor Andreev, was caught out by the weather little more than two hours prior to the start of his match.

Nothing can happen at the summit this week, according to the ATP number crunchers.

Nadal currently stands 770 points behind Federer, who lost his second match in a row after falling to Nadal in a Wimbledon final classic three weeks ago.

The Spaniard could cut that margin to a mere 275 should he win the title on Sunday for a second of his career in Canada.

Nadal, who has beaten Federer in four finals this year including Roland Garros and Wimbledon, continues to play the modesty card.

As usual, Nadal refuses to consider himself the heir apparent despite his recent success, which has featured victories over Federer in four major finals this season, including Roland Garros and Wimbledon.

"Im having a good season, but still I'm still number two, " said the Spaniard. "I still have the same motivation to continue improving.

"If I play like I have over the past four months, I will have my chances for number one."

Australian Open champion Djokovic is equally motivated.

"I just want to keep my focus about my career. If I continue going forward the same way, the results will come," Djokovic said. "I played the best tennis of my career in the first six months of the year."

Federer insists that his slump will not be permanent. And he's got the two major goals in immediate mind.

"I've got to regroup and look forward. The bigger picture is the Olympic Games and the US Open," Federer said. "Those are really the places where I want to win, so I have to make sure I'm ready for that."

In third round play, Croatian spoiler Marin Cilic dealt 2003 Canadian winner Andy Roddick a huge blow as he upset the sixth seed 6-4, 4-6, 6-4.

Britain's Andy Murray left Switzerland without a representative, defeating ninth seed Stanislas Wawrinka 6-2, 0-6, 6-4.

Roddick realises his game is in crisis after coming back from a spring shoulder injury.

"Something doesn't feel comfortable," said the American, who broke a racket after a dispute with the chair umpire concerning an over-rule which the official later admitted he got wrong.

"I keep feeling if I get a couple three, four matches into a tournament I'll be all right," said Roddick, playing for the first time since an early Wimbledon exit.

"I'm not able to do that. It was pretty ordinary out there today. Things are going wrong a little bit across the board. The forehand is just not doing anything, I'm missing it. That's the one that I need to click right now."