The Buffalo Bills' defense is taking another substantial hit.

Former All-Pro linebacker Matt Milano suffered a torn biceps and will be out indefinitely, Bills coach Sean McDermott confirmed Thursday. He will undergo surgery and aim for a possible late-season return, Schefter reported.

Milano, 30, suffered the injury during Tuesday's practice, which he exited early after positional drills.

“It was just a tackle drill. He was tackling on a bag, and he hit his arm,” McDermott said. “We’re all human at the end of the day. Matt’s a heck of a football player, but if we back up, he’s also a tremendous young man, good head on his shoulders.”

It's the second significant injury in less than 12 months for Milano, who suffered a fractured leg in Week 5 of last season.

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“When you know the person, you know it’s not going to beat or keep Matt Milano down," McDermott said. "This has been a tough period for him and for us. No one knows the work Matt put in to get back to where he was before this recent injury. That’s one of the hardest pills to swallow. We just saw him work his butt off, stay in Buffalo to get back from the leg injury, and now this happens.

"It’s unfortunate, but I know he’ll handle it well.”

Milano has been a linchpin of McDermott's defenses since not long after the two arrived in Buffalo in 2017. He broke out in 2022 and earned his lone Pro Bowl and All-Pro nods.

The injury is the latest loss for a Bills defense that has undergone substantial change this offseason. The unit is not returning three of its longtime staples in safeties Micah Hyde and Jordan Poyer and cornerback Tre'Davious White, the latter two being cut in cap-saving moves.

Meanwhile, Bobby Babich takes over as the defensive coordinator after McDermott served as the defensive play-caller in 2023.