Third seed Andy Roddick tumbled out of the Rome Masters when he lost 6-0, 6-4 to last 16 opponent Juan Ignacio Chela on Thursday.
The big-serving American, playing his first tournament since a hamstring injury forced him to pull out of the Miami Masters in March, could not match the metronomic groundstrokes of claycourt specialist Chela in the early stages of the contest.
Chela, who won the claycourt tournament in Acapulco in February, broke Roddick three times on his way to wrapping up the first set in 26 minutes.
Roddick raised his game at the start of the second set, holding serve to love, but three consecutive forehand errors in the seventh game allowed Argentine Chela to gain a decisive break and serve out for the match.
Roddick's defeat continued his relatively poor record in the Italian capital where he had reached the quarter-finals only once in his previous four visits.
In later last 16 matches, world number one Roger Federer takes on Italian wild card Filippo Volandri, while his arch-rival and world number two Rafael Nadal plays 15th seed Mikhail Youzhny.
