BOSTON (CBS) — It’s been a largely uneventful camp for the defending Super Bowl champs, yet an injury to a longtime team captain might change that.

Special teams captain Matthew Slater was absent on Monday when the Patriots and Jaguars took the field for a joint practice session outside of Gillette Stadium.

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Slater suffered an injury last week on Wednesday. As ESPN’s Mike Reiss noted, Slater “could hardly put one leg in front of the other” when walking off the field. Reiss speculated that the injury could be somewhat serious, based on Bill Belichick visiting Slater in the medical tent before Slater was taken inside for evaluation and treatment.

Slater did not participate in Saturday’s workout among injured players, and Monday’s absence will likely fuel some fear that the injury is on the more significant side.

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The 31-year-old Slater was drafted by the Patriots in the fifth round of the 2008 draft. He’s made six consecutive Pro Bowls as a special teamer, and he’s been the special teams captain since 2011. He was also named to the Associated Press’ First Team All-Pro in 2016 for the first time in his career, despite missing three games due to injury.