GREEN BAY, Wis. -- The Green Bay Packers got an injury scare late in Sunday night's loss at Minnesota when Clay Matthews pulled himself out of the game. Although the team did not disclose the reason, the early indications were that it's not serious.

The Pro Bowl linebacker came to the sideline to get his left ankle taped in the first quarter but missed only one snap. He then played 38 of a possible 58 defensive snaps and recorded his second sack in as many games.

However, his night ended with less than two minutes to play. On the first play of the Vikings' final drive, Matthews made a sliding attempt to tackle running back Matt Asiata. Matthews missed and then immediately got up and motioned to the sideline that he needed to come out and ran to the bench under his own power. It did not appear to have anything to do with his left ankle.

"He's got some things we're looking at there," Packers coach Mike McCarthy said Monday. "[He's] just part of the medical [report]; we'll have that for you Wednesday."

When asked whether he had concerns about Matthews' availability, McCarthy said: "Not as of right now. I don't have all the information."

Matthews has not missed a start since he broke his right thumb twice during the 2013 season. He missed four games that year after the first injury, which required surgery, and then re-broke it late in the season and missed two more games, including the playoffs.

Although the Packers would not specify the reason Matthews came out of the game, it was not believed to be related to that thumb injury.

The Packers have a couple of other injury concerns on defense. They already know they will be without defensive tackle Letroy Guion, who has a sprained MCL that will keep him out until after the Week 4 bye. Safety Morgan Burnett (hamstring) also was going through medical tests on Monday.

Cornerback Sam Shields also remains in the concussion protocol. He sustained his fourth career NFL concussion in Week 1 and did not play against the Vikings. McCarthy said Shields was at the facility for a workout on Monday but did not have any further update.