World number one Rafa Nadal [ Images ] survived a scare and Roger Federer [ Images ] ended a run of recent losses to Tomas Berdych to lead the world's top four players into the semi-finals of the Toronto Masters on Friday.

Defending champion Andy Murray [ Images ] and world number two Novak Djokovic [ Images ] also posted quarter-final wins to complete the all-star quartet but it was the possibility of a Nadal-Federer final that had tennis fans buzzing at the end of riveting day of action on the Canadian hardcourts.

Playing in his first event since winning Wimbledon [ Images ] last month, Nadal has at times appeared to still be in holiday mode, and the Spaniard was again slow out of the blocks against Philipp Kohlschreiber rallying for a nervy 3-6, 6-3, 6-4 win.

While Nadal could not have expected such a punishing workout from the 37th ranked German, who has just one win over a top 10 ranked opponent this season, Federer stepped onto centre court knowing the giant challenge that awaited him and responded with an inspired 6-3, 5-7, 7-6 victory over Berdych.

The towering 1.96 metres Czech has had Federer's measure this season beating the Swiss twice, including an upset win in the quarter-finals at Wimbledon.

"It's sort of hard to put a rank on it, but it's nice always winning matches 7-6 in the third," Federer told reporters.

"Today I just think I had a good start to the match, had chances in the second and then it was just kind of one of those matches I thought was going to slip away again like at the beginning of the season.

"But I was able to turn it around. It was definitely huge at this point," he added.

Berdych had looked poised to continue his winning sequence over Federer when he stormed to a 5-2 lead in the third but a relentless Federer refused to fold, finally getting the break he needed with Berdych serving for the match at 5-3.

With a breathless centre court crowd on its feet, there was more drama to come during a pulsating tiebreak that saw Federer jump ahead 4-0 then grimly hang to clinch the victory 7-5 when Berdych sent a return into the net.

Murray, who must at least reach Sunday's final to keep his number four ranking, produced his best effort of the week, easing to a 6-2, 6-2 victory over red-hot David Nalbandian [ Images ], ending the Argentine's 11-match winning streak.

Djokovic, the Canadian champion in 2007, also had smooth passage into the last four beating France's [ Images ] Jeremy Chardy 6-2, 6-3.