Defensive tackle Hollis Thomas, who fractured his right foot during practice last Friday, will undergo surgery on Thursday and be out of the Philadelphia Eagles' lineup for a still undetermined period of time.

Thomas was examined by a foot specialist in Chicago on Monday and he recommended the surgery. The team won't have a clearer prognosis on Thomas' possible return later in the season until after the operation.

The six-year veteran is a solid defender against the run, and started 14 games in 2001, but broke his right foot in a Dec. 30 game against the New York Giants and was sidelined for the playoffs. It is believed that Thomas suffered the latest injury during one-on-one drills in the Friday morning practice.

Thomas, 28, had 70 tackles, eight quarterback pressures, four forced fumbles and a recovery last season. For his career, he has 263 tackles and 13½ sacks in 90 games and 79 starts.

Initial speculation was that the Eagles, who already lost three defensive starters from the 2001 starting lineup earlier in the spring, might pursue free agent tackle Sam Adams, the premier player still available in the unrestricted market. But the agent for Adams said on Monday afternoon he has not been contacted by Philadelphia officials.

For now, it appears the Eagles are content to replace Thomas with the tandem of Paul Grasmanis and Darwin Walker.

Philadelphia faces Green Bay in the preseason opener for both teams on Saturday and will wait until after that contest to determine if it should add another veteran tackle.

Len Pasquarelli is a senior writer for ESPN.com.