FOXBORO -- The Patriots don't have all of their ducks in a row quite yet as training camp gets underway.

But with three draft picks still unsigned as of Wednesday night -- an unusual circumstance for them -- the defending world's champions tapped the market of available free agents to shore up their depth.

With starting left tackle Matt Light on the physically-unable-to-perform list because of his gradual recovery from a June appendectomy, the Patriots signed veteran insurance in the form of former Pro Bowl offensive tackle James `` Big Cat'' Williams. They also added more competition along their revamped defensive line by adding free agent Dwight Johnson. Terms of both veterans' contracts were not disclosed.

At the same time, exclusive-rights free agents Tom Ashworth and David Givens were brought back into the fold with their signings of one-year tender offers.

Still unsigned as of late Wednesday were the 32nd selection overall, tight end Benjamin Watson of Georgia; third-round selection Guss Scott, a safety from Florida; and fourth-round pick Cedric Cobbs, a running back from Arkansas. If they remained unsigned today, it would have marked the first time since running back J.R. Redmond held out in 2000 that the Patriots have not had all of their draft picks in camp at its opening -- and only the second time that's happened since Robert Kraft assumed ownership of the franchise in 1994.

Williams, 36, is a veteran of 12 NFL seasons, having played in 166 games with 143 starts for the Chicago Bears from 1991-2002. The 6-foot-7, 332-pound tackle started on the right side in 134 consecutive games for the Bears, including every game in his final eight seasons in Chicago.

Williams, nicknamed ``Big Cat,'' was originally signed as an undrafted free agent defensive lineman out of Cheyney (Pa.) State in 1991. He played in 19 games as a reserve defensive tackle in his first two pro seasons, then began a transition to the offensive line following the 1992 season. He became a full-time starter there in 1994.

In 2001, his Pro Bowl season, he was selected by his teammates as the winner of the Brian Piccolo Award, given both to a Chicago veteran and a rookie who best exemplifies, courage, loyalty, teamwork and dedication.

Johnson, 27, begins his third NFL season with the Patriots after having played for the New York Giants in 2002 and the Philadelphia Eagles in 2000. He has played in 14 regular-season games and one playoff game, with two starts.

The 6-foot-4, 290-pound native of Waco, Texas, has recorded 14 career tackles (10 solo). He was originally signed by the Eagles as an undrafted free agent out of Baylor, and played for the Frankfurt Galaxy of NFL Europe in 2001.

Ashworth, last year's starting right tackle, and Givens, a seventh-round pick from Notre Dame two years ago who had an outstanding playoff run last season, will both play for the third-year minimum of $380,000 according to published reports.

Both will be restricted free agents next year unless they agree to extensions.

MARK FARINELLA may be reached at 508-236-0315 or via e-mail at mfarinel@thesunchronicle.com.