GREEN BAY, Wis. – Clay Matthews kept playing after he injured his left ankle in last Sunday’s loss at the Minnesota Vikings. It was a hamstring injury that prevented him from finishing it.

Both could be problematic for the Green Bay Packers outside linebacker leading up to this week's home opener against the Detroit Lions.

Matthews did not practice on Wednesday, one of five key defensive players sidelined. Both of Matthews' ailments were listed on the injury report.

Clay Matthews made his presence felt while he was on the field last Sunday, but ankle and hamstring injuries sidelined him before the day was done. Brace Hemmelgarn/USA TODAY Sports

Coach Mike McCarthy expressed minimal concern over Matthews’ health on Monday, but appeared less certain on Wednesday.

"[Matthews] went through treatment this morning [and] did extensive work in the strength and conditioning," McCarthy said before Wednesday's practice.

Matthews left last Sunday's game to get his left ankle taped and returned for the next series. He played until late in the fourth quarter, when he pulled himself out after trying to make a sliding tackle. That's apparently when he sustained the hamstring injury.

Matthews attended Wednesday's practice but rode an exercise bike and an elliptical machine off to the side in the Don Hutson Center.

Matthews' history with hamstring injuries could be cause for concern, although he hasn't missed a game because of that since Dec. 9, 2012. Matthews missed practice time as a rookie in 2009 because of hamstring injuries and missed a game in 2010 for the same reason. He has not missed a game since he sat out the final two games of the 2013 season after breaking his thumb for the second time.

In his return to outside linebacker after spending the previous year and a half on the inside, Matthews has a sack in each of the first two games.

The biggest concern for the Packers might be that five key contributors did not practice on Wednesday.

It's an ankle and a hamstring for Clay Matthews. Both have been problems for him in the... https://t.co/EGvWpmopZt pic.twitter.com/V45o1SX6OX — Rob Demovsky (@RobDemovsky) September 21, 2016

Cornerback Sam Shields (concussion) and defensive tackle Letroy Guion (knee) aren't expected to play against the Lions. Safety Morgan Burnett (groin) and defensive end/outside linebacker Datone Jones (knee) also did not practice.