A two-time beaten finalist here and the reigning Australian Open champion, Federer uncharacteristically made 44 unforced errors in his shock 6-2, 6-4 defeat to the Italian wildcard ranked 53rd in the world.

Defeat means Federer has now gone four tournaments without winning a title, his longest stretch without a trophy since he became world number one in February 2004.

"I played shocking," was Federer's brutal assessment of his own performance.

"I just couldn't get into the game. I was serving horrendous, and you don't get any free points on clay if you are not serving well.

"It is very disappointing to go out at this stage of the tournament, but it does happen in tennis.

"But everyone's talking about me, but give credit to Filippo. He played a great match."

Asked if he could take any positives from his shock exit, Federer replied: "It gives me more time to practise for the French Open."

Volandri said it was a dream come true to defeat Federer on home soil.

"It's more than a dream, more than I could have hoped for," said the 25-year-old.

Earlier on Thursday American third seed Andy Roddick was bundled out 6-0, 6-4 by Argentina's Juan Ignacio Chela.

Roddick, a semifinalist here in 2002, struggled with his serve and made 27 unforced errors as Chela recorded only his second victory over the former world number one in eight meetings.

Ranked 23 in the world, Chela will now face the winner of the all-Chilean clash between sixth seed Fernando Gonzalez and Nicolas Massu.

Roddick admitted he gave himself too much to do after his poor first set display.

"I dug a hole for myself in the first 10 minutes," said the 24-year-old.

"After that it was an uphill battle. I started playing better in the second set, but it was too little, too late."

Chela, who has never reached the Rome quarterfinals before, was delighted with his performance at the Foro Italico.

"I played the perfect match," said the 27-year-old, winner of four ATP titles.

"The first set was fairly straightforward and allowed me to save some energy for the second.

"That helped me a lot as Roddick played much better in the second set."

The Rome Masters is a warm-up event for the French Open, the second Grand Slam of the year which starts on May 27.