But two more seeds were sent out on the clay on Day 2, with Frenchman Jeremy Chardy upsetting Spanish No. 14 Albert Montanes 6-3, 7-6 (7/1) and 92nd ranked home qualifier Daniel Gimeno-Traver defeating Argentine No. 15 Juan Monaco 6-2, 3-6, 6-2.
It was a day of drama off-court as Rafael Nadal detailed his reasons for withdrawing as a precaution from one of the events which is closest to his Spanish heart and where he has won the last five editions.
"It's been a tough year," said the world No. 3, who expressed his disappointment at being forced to let down his home club and public.
"My goal is to remain healthy and fit," said a player well acquainted with injury absences due to the delicate state of his knees.
Nadal said that three straight weeks of elite clay events — Monte Carlo, Barcelona and Rome — were too much in too short a period, another knock at the ATP calendar which he has long complained is helping to cause player injuries and burnout.
"I'm being as cautious as possible, I want to have as long a career as possible," said Nadal, who lost his only match in Barcelona in 2003.
"Tennis isn't like football, you don't know how many matches you will play." He is expected to return for Rome next week.
The 12th-seeded Hewitt went missing for eight years at the Real Club de Tenis, where he challenged as world No. 1 for a place in the 2002 final but lost his semifinal to eventual champion Gaston Gaudio.
In the intervening years, the former Wimbledon and US Open winner played sparingly on the spring European clay, due partly to his natural disposition for hardcourts and also later due to injuries which have included two hip surgeries.
But Hewitt showed no ill effects as he began his European clay season with the goal of doing well in the run-up to Roland Garros next month.
The Australian fired 10 aces and broke six times against Turkey Ilhan, who could be the key to a possible upset of Britain in a do-or-die Davis Cup playoff in July for his nation.
Hewitt saved four of the five break points he faced in a victory lasting just under two hours.
The 29-year-old Aussie, who underwent right hip surgery on January 29, is playing in his second tournament back after Houston, where he reached the quarterfinals before losing to Juan Ignacio Chela.
Hewitt's win marked only his sixth of an abbreviated season against three losses. In second-round play, Spaniard Ivan Navarro Pastor advanced over Pablo Cuevas of Uruguay 6-2, 6-4 while 15th-seeded Nicolas Almagro also won in straight sets.
Italian qualifier Simone Bolelli advanced to the second round after ninth-seeded Tommy Robredo retired Tuesday while trailing 7-6 (7), 4-6, 1-3 due to an unspecified injury.
Jurgen Melzer, seeded 11th, also advanced along with Sergiy Stakhovsky.
