GREEN BAY, Wis. — Outside linebacker Pernell McPhee was activated Thursday afternoon from the physically-unable-to-perform list six days after he began practicing for the first time since January.

McPhee had arthroscopic knee surgery early in the off-season but was slow to recover. Before the injury hobbled him in the second half of last season and caused him to miss two games, McPhee was arguably the Bears’ best defender with 5 of his 6 sacks in the first seven games.

The defense has missed that most of all. Subtract Willie Young’s 6 sacks, and the rest of the team has just 7.

“Any time you lose a good player — and he was a good player the first half of last season — it’s going to have a negative effect,” defensive coordinator Vic Fangio said.

After the Bears’ non-padded practice on Tuesday, Fangio was asked how much McPhee could help against the Packers.

“I don’t know to be honest with you,” he said. “We’ve got to see how he’s moving around, how he’s playing. All we’ve had with him was last Friday, which was a low-tempo practice (with) no pads.”

This week’s practices were also low tempo because of the short week.

McPhee did not start but played in the first half without making an impact. Much of the uncertainty about McPhee’s ability to contribute stemmed from the Packers’ propensity to operate without a huddle, meaning defenders have to be able to stay on the field longer and in various situations.

“He’s got to be able to fill in and play just like everybody else,” Fangio said.

More reinforcements:

In addition to McPhee, the Bears also welcomed back first-round rookie outside linebacker Leonard Floyd, who missed the previous two games with a calf injury. Floyd had a strip sack, a fumble recovery and a touchdown, which gave the Bears a 10-6 lead. It was the only TD the Bears scored.

Defensive coordinator Vic Fangio cautioned not to expect too much from either Floyd or Pernell McPhee.

“Obviously they can’t play 60 plays — either one of them,” Fangio said.

“So, when they get their plays, if they do play, they’ve got to make the most of them. And they’ve got to be ready to go. And in this game, they’ve got to be prepared to stay out there maybe a little bit longer.”

Floyd got the Bears’ only sack of the first half, when he dropped Aaron Rodgers for a 9-yard loss.

Sitting it out:

Thursday night’s inactives were quarterback Jay Cutler (right thumb), guard Josh Sitton (ankle), nose tackle Eddie Goldman (ankle), running back Jeremy Langford (ankle), wide receiver Eddie Royal (toe), cornerback Deiondre’ Hall (ankle) and safety DeAndre Houston- Carson.

Cornerback Bryce Callahan (hamstring) was active, but not 100 percent so first-year player De’Vante Bausby got his first NFL start with Cre’Von LeBlanc as the nickel. Callahan replaced Bausby on the second possession but both played after that.

Eric Kush started at left guard in place of Sitton. Hall and Royal did not make the trip to Green Bay.

For the Packers, No. 1 running back Eddie Lacy (ankle) was placed on injured reserve and his backup, James Starks (knee) was inactive. Starting in their stead was undrafted rookie Don Jackson, who was promoted from the practice squad.

The only other running back on the roster is Knile Davis, who was acquired in a Tuesday trade with the Chiefs.

Both Packers starting cornerbacks — Damarious Randall and Quinten Rollins — were inactive, as was starting tight end Jared Cook.

Feeling at home:

Thursday night’s game was the Packers’ fourth straight at home, the first time they’ve enjoyed a homestand that long since 1963. They haven’t played on the road since Sept. 18. The game also marked the 11th consecutive season in which the Bears and Packers have played in prime time.

Back and forth:

Fullback Paul Lasike was waived to create the roster spot for Pernell McPhee, but is expected to be re-signed to the practice squad.

Lasike played in four games with 2 carries for 3 yards and spent Weeks 3-4 on the practice squad.

• Follow Bob LeGere’s Bears reports on Twitter at @BobLeGere.