Pete Sampras has withdrawn from next week's Italian Open in Rome, joining world number two Lleyton Hewitt among the high-profile absentees.

US Open champion Sampras gave "no reason" for withdrawing, ATP Tour spokesman Rob Penner said.

"He's still making up his mind on what he wants to do with his tennis," said Penner.

"And the way these tournaments are set up he has to withdraw each time."

Sampras has requested and been granted a wild card for the Wimbledon warm-up tournament at Queens Club.

He has not played since winning at Flushing Meadows in September and, if he is to make a comeback, it seems increasingly likely it will be in the grasscourt season.

Hewitt has withdrawn after being told by his doctors to rest.

His management announced on Wednesday that Hewitt would make his season's clay-court debut at the German Open in Hamburg on 12 May.

Hewitt will then play for Australia with Wayne Arthurs in the World Team Cup in Dusseldorf the following week.

Hewitt's 75-week reign as world number one ended at the weekend when American Andre Agassi won the US clay court title in Houston, Texas.