World number one Roger Federer will work with renowned clay-court coach Jose Higueras this week as he begins his preparations for the French Open.

Federer, who has been without a coach since May 2007, will work with Higueras at the Estoril Open in Portugal.

"He's one of the world's most respected and accomplished coaches," said Federer, who only needs a French Open title for a career Grand Slam.

"We are going to see if we could make a good team."

Spaniard Higueras reached two semi-finals at Roland Garros as a player and went on to coach 1989 champion Michael Chang.

He has also worked with Americans Jim Courier, Pete Sampras and Robby Ginepri and is highly regarded as a clay-court specialist.

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Federer has won 12 Grand Slam titles but is yet to conquer Roland Garros, falling to Rafael Nadal in the last two finals.

The 26-year-old has had a poor year by his high standards and is yet to reach a final in four tournaments so far.

That constitutes his worst run since 2000, when he was ranked outside the world's top 50.

After falling in straight sets to Novak Djokovic in the Australian Open semi-finals, Federer admitted he had been suffering from glandular fever.

He subsequently lost to Andy Murray in his opening match in Dubai before suffering defeats by Mardy Fish and Andy Roddick on the American hard-courts.

Federer faces Belgium Olivier Rochus in his first match in Estoril, where he is the top seed ahead of Nikolay Davydenko.