Yahoo! Sports earlier reported Mayo's condition.
Mayo, a team captain, was injured in the fourth quarter of the Patriots' 30-27 victory against the New Orleans Saints on Sunday. He was spotted leaving Gillette Stadium with his right arm in a sling.
One of the Patriots' few defenders in the front seven who plays on all downs, the six-year veteran also had the important job of leading the team's defensive huddle, getting the play call in from the sideline and relaying it to teammates. Mayo is a two-time Pro Bowler and was a 2010 first-team All-Pro selection who has led the Patriots in tackles in each of his first five seasons with the club.
In the Patriots' base 4-3 defense, Mayo has mostly played the weak side, with Brandon Spikes in the middle and Dont'a Hightower on the strong side. Rookie Jamie Collins, the Patriots' top draft choice (52nd overall), is a leading candidate to step in for Mayo. Four-year veteran Dane Fletcher, whose primary contributions have come on special teams, is another option.
Meanwhile, Hightower is the top choice to lead the huddle on early downs (he did so Sunday after Mayo left with injury), but because he sometimes doesn't play in sub packages, the Patriots might consider other possibilities for that role.
The Patriots previously lost defensive captain Vince Wilfork to a season-ending torn Achilles on Sept. 29. That injury, coupled with Mayo's, hits at the heart of the team's much-improved defense.
On Monday, when asked about Mayo's potential absence, Patriots defensive end Rob Ninkovich said, "A guy like Mayo is a great leader and a great teammate. ... We all work together, and it's a team defense here. If guys like myself have to have more of a leadership role and do a little more, that's all right with me."