Djokovic, Federer in heavyweight semi-final clash

Novak Djokovic and Roger Federer will clash for the 25th time in Saturday's Rome Masters semi-finals while Rafael Nadal also progressed, ensuring the big three all made the last four of this crucial French Open warm-up.

Defending champion Djokovic, the top seed, fought through the first set, before racing away in the second to beat French fifth seed Jo-Wilfried Tsonga 7-5, 6-1.

Federer, fresh from his Madrid Masters triumph last weekend, followed the script with a 6-1, 6-2 demolition of Italian Andreas Seppi in just 53 minutes, with the Swiss third seed winning 14 of the first 15 points.

Roger Federer. Pic/AFP

Second seed Nadal, meanwhile, got the better of Czech seventh seed Tomas Berdych, grinding out a 6-4, 7-5 win.

"In the second set I played one of the best sets on clay this year," said Serb star Djokovic.

"This is encouraging for the challenges ahead. With Roland Garros coming, I'm playing and feeling better in every match."

Djokovic was tested early on by Tsonga in a first set filled with five breaks of serve. But after winning the opener in nearly an hour, Tsonga's defences collapsed as the top seed came home for his 29th win of the season.

"I really don't compare with 2011 (when he won three of the four majors). This is a new year and I have had great results so far," added Djokovic.

Rome is one of the few big events Federer has not won, losing finals in 2003 and 2006.

But the Swiss star, who hasn't played Djokovic since his marathon US Open semi-final defeat last year, showed his clay game is nearing perfection, just a week before the start of the French Open.

Nadal will face off in the final four against compatriot and sixth seed David Ferrer, who beat French 15th seed Richard Gasquet 7-6 (7/4), 6-3.

"I played one of my best matches on clay against a difficult opponent," said five-time Rome winner Nadal.

"I'm happy to do so well after also playing well in Monte Carlo and Barcelona (where he won both titles). It was a big match because the level of the opponent was high and he plays with big confidence. I played under pressure all the time."

Nadal and Ferrer went toe-to-toe less than three weeks ago, with Nadal winning the final to take his seventh trophy on home clay in Barcelona.

Nadal showed he has regained his blistering form after a poor third-round loss a week ago on blue clay in Madrid as he beat Berdych for the 11th time in succession in a struggle lasting just over two hours.

Novak Djokovic. Pic/AFP

The French Open champion produced 34 winners and just 10 unforced errors in a superlative display, while Berdych went for broke throughout, posting 28 winners and 24 unforced errors and losing serve three times.

World number three Nadal has now won all but two of his 36 matches at the Foro Italico and has emerged victorious in all three clay meetings with a player he also beat in the 2010 Wimbledon final.

Meanwhile, Ferrer needed an hour and three-quarters before putting out Gasquet, who played the Estoril final on clay earlier this month.

The gutsy Spaniard, who is still seeking his first title this season, is through to the quarter-finals in Rome for the first time.u00a0