Reagor was elevated from the Chargers' practice squad to the active roster Monday, Kris Rhim of ESPN.com reports.
Reagor has yet to play this season, but he did suit up 11 times for the Patriots last season, making seven catches on 23 targets for 138 yards while also handling some return duties. The 25-year-old could see a considerable workload depending on who suits up for the Chargers. Aside from Quentin Johnston (ankle), who carries a doubtful tag, the Chargers are also listing fellow wideouts Ladd McConkey (hip), Simi Fehoko (shoulder) and Derius Davis (hamstring) as questionable for MNF against the Cardinals.