The latest update on New England Patriots rookie Will Campbell’s knee injury pours a bucket of ice water on the initial assumption that the offensive tackle had avoided a major knee injury.

According to NBC Sports Boston’s Albert Breer, Campbell suffered a Grade 3 MCL sprain in the team’s Week 12 win over the Cincinnati Bengals. There is still hope within the Patriots’ organization that he will return for the regular season finale, but even Breer admitted that timetable would be pushing it for an injury he called “very significant.”

“This is a very significant injury. He has a Grade 3 MCL sprain. That essentially means his MCL is torn,” said Breer. “It’s a four-to-six-week injury. One of the reasons they decided to put him on injured reserve was actually to protect him from himself.

“They felt like because of who he is, how tough he is, the sort of competitor that he is, that he would push to get back earlier than that. …They’re going to try and get him back for the last game of the regular season. Even that may be pushing it a little bit. This is not a minor injury, though. This is an MCL tear.”

The Patriots could err on the side of caution and keep Campbell out for the rest of the regular season. If the team wins the No. 1 seed in the AFC, they would get a first-round bye in the playoffs, and Campbell would be guaranteed an extra week of recovery time.