The Boston Herald, meanwhile, cited a source close to the situation in reporting that it's more likely Welker will begin camp on the active physically unable to perform list as a precaution, depending on the medical staff's evaluation.
If Welker went on the active PUP list, he would be ineligible to practice but could be removed from list. If he goes on the reserve PUP list, he would miss at least the first six weeks of the season.
Welker, a two-time Pro Bowl pick, surprised many this offseason by returning to the practice field in June, just four months after his surgery. Welker tore his left anterior cruciate ligament and damaged the medial collateral ligament, which didn't require surgery, without being touched when he planted his left leg after making a short reception during the Patriots' Jan. 3 regular-season finale at Houston.
The Associated Press contributed to this report.