Tight end Rob Gronkowski tore the ACL and MCL in his right knee during the New England Patriots' 27-26 comeback victory Sunday over the Cleveland Browns, a league source told ESPN NFL Insider Adam Schefter on Monday.

Rob Gronkowski was carted off the field after suffering an injury to his knee against Cleveland. AP Photo/Steven Senne

He was officially placed on season-ending injured reserve Monday afternoon. The Patriots signed tight end D.J. Williams, who they released last week, to fill Gronkowski's roster spot.

Gronkowski suffered the injuries in the third quarter after hauling in a pass up the seam from Tom Brady. The two-time Pro Bowl tight end took a direct hit to his right knee from Browns safety T.J. Ward and fell to the ground, clearly in pain.

Brady said Monday the Patriots' formula at tight end must shift without Gronkowski.

"You just have to find a different formula," Brady told the "Dennis & Callahan Show" on WEEI sports radio in Boston, when asked whether the team's other tight ends are capable of doing what Gronkowski does. "I think that's the important part. And Gronk provides a certain margin of error because of how talented a player he is, and the other guys play different roles for us."

Running back Shane Vereen, who had 12 catches for 135 yards (a franchise all-time best for a running back) Sunday, figures to be more of a focal point in the passing game with Gronkowski out.

"I think we'll be able to stay very similar," Vereen said. "Of course, we're going to have to adjust some things but I can't tell you everything we're going to have adjust; we don't have the game-plan for this week yet. We're all going to have to step up, we're all going to have to take on bigger roles."

The Patriots have two other tight ends on the roster, veterans Matthew Mulligan and Michael Hoomanawanui, who missed his third straight game Sunday. In addition, fullback James Develin has taken snaps at tight end on an as-needed basis.

"Those roles are going to have to shift, kind of what we did on the last two drives of the game," Brady said. "We had four receivers at points, at different points we had more [tight ends] with Develin and Mulligan on the field."