Roger Federer's dreams of winning his first Rome Masters title were shattered when he slumped to a 6-2, 6-4 defeat against Italian wildcard Filippo Volandri in the third round on Thursday.
Third seed Andy Roddick followed the world number one out of the claycourt tournament, losing 6-0, 6-4 to Juan Ignacio Chela, but defending champion Rafael Nadal remained on course for a hat-trick of Rome titles.
The Spaniard appeared to have overcome the dizzy spells that troubled him in the previous round and was back on form with a 6-2, 6-2 win over 15th seed Mikhail Youzhny.
Fourth seed Nikolay Davydenko also reached the quarter-finals with a 4-6, 6-2, 7-5 win over Italy's Potito Starace.
Federer, runner-up in Rome in 2003 and 2006, barely resembled the player who battled with Nadal in last year's thrilling five-set, five-hour final as he made 44 unforced errors to hand Volandri victory.
The defeat means the Swiss has gone four tournaments without a title -- his longest stretch since becoming world number one in February 2004.
"It's disappointing but there's nothing you can do about it. That's knock-out tennis," said a downcast Federer, denying he was ill or injured and dismissing the heat on Rome's centre court as a contributing factor to his defeat.
"I played good in my first match (to beat Nicolas Almagro), and usually after the first game I play better and better but today was the opposite.
"On clay you need to be solid and I wasn't. I don't know if you can say I was playing shockingly but I was making a lot of mistakes, serving badly -- giving him second serves all the time.
"It sometimes happens but usually I get through. And Volandri played well. Everyone is talking about how I played, but he already played well against (13th seed Richard) Gasquet (in the previous round).
"I know his game. I played a tough match against him here a few years ago, I played him in the juniors, so I know how tough he can be."
NEAR-PERFECT MATCH
Nadal showed few signs of vulnerability as he extended his winning streak on clay to 74 matches.
The 20-year-old Spaniard had undergone medical checks after suffering a dizzy spell during Wednesday's second-round win over Daniele Bracciali, but seemed his usual bustling self as he swept Youzhny aside with the minimum of fuss.
"I played a near-perfect match today," said Nadal, whose next opponent, fifth seed Novak Djokovic, beat Marcos Baghdatis 6-2, 7-5.
Asked whether Federer's exit had cleared his way to equal Thomas Muster's professional era record of three Rome titles, Nadal replied: "No. I don't think so. There are still some very difficult matches to come, starting with the game against Djokovic."
Roddick's defeat came as little surprise. The big-serving American, who was playing his first tournament since a hamstring injury forced him to pull out of the Miami Masters in March, was no match for claycourt specialist Chela.
"I served horribly today and that made the rest of it a little tough for me," said Roddick.
"I actually started hitting the ball a little better in the second set and that allowed me to get in a little bit more. But I dug a good hole for myself in the first 10 minutes out there today."
In the quarter-finals Chela will play sixth seed Fernando Gonzalez, who beat Nicolas Massu 6-7, 6-3, 6-4.
