Weatherspoon was helped off the field after playing 47 snaps. He was hopeful the injury wasn't going to be serious after feeling soreness in his Achilles and calf afterward. An MRI on Monday morning revealed the worst-case scenario.
Weatherspoon, who was a first-round draft pick of the Falcons in 2010, also missed the entire 2014 season after tearing his left Achilles. Injuries have plagued his career, but Weatherspoon experienced a resurgence this season upon re-signing with the Falcons after a one-year stint with the Arizona Cardinals.
He expressed a positive outlook and a desire to continue his career, despite his latest setback.
"My headspace is awesome man," Weatherspoon said in a text message to ESPN. "I'm blessed. I showed that I can play at a high level again. I'll do it again, with God's unchanging hand."
Weatherspoon is third on the team with 27 tackles. He signed a one-year deal with a base salary of $1 million with just $150,000 fully guaranteed. The deal included roster bonuses of $31,250 per game on the 46-man roster, with a maximum value $500,000.
The Falcons are thin at inside linebacker with Weatherspoon out and rookie De'Vondre Campbell (ankle) along with Paul Worrilow (groin surgery) still recovering from injuries. Weatherspoon replaced Campbell in the starting lineup at weakside linebacker, while Worrilow was beaten out by rookie Deion Jones for the starting spot at middle linebacker.