Updated

By Steve Keating

TORONTO (Reuters) - A Rafa Nadal-Roger Federer final remains one of the most mouthwatering matches in tennis and the Spaniard set the stage for another classic showdown on Friday, calling his rival on the other side of the Canada Masters draw.

Back on top of the world rankings, a relaxed Nadal fittingly conducted the draw for the August 9-15 tournament high up in Toronto's CN Tower where his first task was to pick either Federer or Briton Andy Murray to line up alongside him.

Staring at the two chips, a playful Nadal laughed when placing Federer with second seed Novak Djokovic on the other side of the bracket, leaving himself with the prospect of a semi-final against defending champion Murray.

Federer and the CN Tower -- once the world's tallest free-standing structure -- have slipped in the rankings but both remain popular attractions in Canada.

PUNISHING SURFACE

"It's a very important part of the season and for me every tournament is very important," Nadal told reporters.

"Winning three grand slams, and we are speaking about the U.S. Open, is going to be a goal but I can only try my best all the time.

"For me this tournament is the most important thing."

The North American hardcourt campaign has proved the most punishing part of the season for Nadal, the unforgiving surface exacting a heavy toll on his fragile knees.

But this year Nadal comes into the event rested after taking three weeks off to undergo what he called "prevention treatment," a break that included watching Spain win the soccer World Cup in South Africa.

He returned to practice about 10 days ago but continues to ease back into action, and said he would warm up for the tournament by playing a round of golf on Saturday.

In contrast to Federer, who faces his Wimbledon conqueror Tomas Berdych and 2007 champion Djokovic, Nadal's draw has fewer hurdles, a possible quarter-final against eighth seed Andy Roddick likely to be the first major test.

The Spaniard takes on either Canadian wild card Frank Dancevic or Swiss Stanislas Wawrinka after a first-round bye.

"I feel good," said Nadal. "I had a very good grass court season, clay court season and I was in the semi-finals in Indian Wells and Miami.

"Right now I am (in) perfect condition."

(Editing by Ian Ransom)