
Hewitt has never been past the third round at the Foro Italico, losing in his first match last year before reaching a surprise semi-final in Hamburg a week later.
Australian media reported that the former number one is still struggling with the left hip injury which he picked up in March at Indian Wells on cement.
His French Open fitness is now under scrutiny, with the Hewitt camp said to be hoping for a clay debut at Hamburg, now little more than a week away.
Hewitt, ranked 20th, has been receiving treatment for his problem at home in Sydney. His only recent tennis came in a Davis Cup when he led Australia past Thailand in a playoff tie.