Djokovic stretches unbeaten run with imperious win

(CNN) -- Novak Djokovic stretched his unbeaten run to 16 matches as the World No.1 was joined in the semifinals in Dubai by five-time winner and defending championRoger Federer Thursday.

Djokovic has been in imperious form at the hard court event and was never troubled by quarterfinal opponent Andreas Seppi of Italy, winning 6-0 6-3 in 64 minutes.

Federer was equally impressive against Russian veteran Nikolay Davdenko, dropping just four games in a straight sets romp.

But they face much tougher tests in the last four clashes Friday, with Djokovic playing in-form fourth seed Juan Martin del Potro of Argentina and Federer taking on third ranked Tomas Berdych, who beat him in the quarterfinals of the U.S. Open last year.

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It is the first time in the history of the 20-year-old Dubai Open that all top four seeds have reached the semifinals and del Potro and Berdych were largely untroubled in their last eight clashes.

Del Potro outclassed World No.97 Daniel Brands 6-4 6-2 while Berdych overpowered Russian wild card Dmitry Tursunov 6-3 6-2 in just over an hour.

Australian Open champion Djokovic's streak dates back to November last year, but he knows he will have to be on top of his game against del Potro, who won in Rotterdam earlier this month.

"Delpo is a very talented player, very powerful from the baseline and with a big service. We know everything about each other, it's going to be a tough one and I need to be on top of my game," he told the official ATP website.

World No.2 Federer knows formidable Czech Berdych will offer a difficult test as he bids fora place in the final and his 77th career title.

"He's obviously a good player. He's got amazing power, one of the strongest guys out there on tour. We'll see tomorrow how it goes. I haven't seen him play at all here this tournament. I need to just focus on my game," said the Swiss.

In Federer's favor may be the tough schedule of his opponent, who had to fly from Marseille where he lost to Jo-Wilfried Tsonga of France in Sunday's final.

Tsonga also made the long trip, but exited in the first round to fellow Frenchman Michael Llodra.