The New England Patriots placed tight end Rob Gronkowski on injured reserve with a torn anterior cruciate ligament and torn medial collateral ligament.
Gronkowski's loss is a blow to the Patriots' offense.
Gronkowski was replaced on the active roster by tight end D.J. Williams.
He was re-signed after being cut last week.
Williams, 25, played in seven games with one start for Jacksonville this season before being released by the Jaguars in November.
The 6-foot-2, 245-pounder originally entered the NFL as a fifth-round draft pick by Green Bay out of Arkansas in 2011. He has played in 34 NFL games with three starts and has nine receptions for 70 yards.
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Aaron Wilson covers the Ravens for The Baltimore Sun.