Minutes later, he walked back on to the field and threw warm-up passes with backup DeShone Kizer before the start of the second half.
Aaron Rodgers put together a performance on one leg many quarterbacks couldn't do with two.
NBC flashed a graphic saying Mack was the first player to record a sack, interception, touchdown, forced fumble and fumble recovery in a single half - it also said since 1982, but that's the year the National Football League started keeping sacks as a statistic, so Mack could be the only player ever to do that in one half.
The offense was versatile, explosive, exciting and productive as Matt Nagy took his bag of tricks he'd been hiding throughout the preseason and dumped it out all over Lambeau Field. So there's that. One of the most impressive things about this is that Pettine had the success that he did with just three safeties; both Josh Jones and Raven Greene were inactive. Cobb proved he was worth his contract with his 75-yard catch-and-run for the winning score.
What we learned at Green Bay is this is a much improved football team that isn't ready for prime time yet, but just may be a little sooner than we expected.
With 13:37 in the first quarter, Mack entered the game and quickly made his presence felt.
The news didn't go down too well with some of his team-mates, who feel that one of their star players has hung them out to dry - and perhaps Bell could have made the difference in their draw at Cleveland.
When Mitchell Trubisky and the offense didn't do anything with that turnover, Mack chose to just do things himself: Kizer was hit by Roy Robertson-Harris as he released the ball on third-and-long inside Packers' territory and Mack snagged the ball out of the air, running it in 27 yards for the touchdown and a 17-0 Chicago lead. On the Packers' next offensive series, Mack brought pressure on the left side and got his hands around Kizer's feet. "That's why he's here and continues to makes plays". We're still going to own you.
Catch Osi Umenyiora and Jason Bell on the NFL This Week every Tuesday on BBC Two and the NFL Show on Saturdays on BBC One or on the BBC iPlayer.
- Hi, welcome to my new Monday column entitled "Game Notes".
It took newly acquired Bears linebacker Khalil Mack just 83 seconds to introduce himself to Bears faithful on Sunday night - and then he reintroduced himself again and again. He joins Mark Rypien in that exclusive club.
"I just told him I've got to be in the pistol or the shotgun and not go under center", Rodgers said.
How - if at all - will Rodgers be limited by his left-knee injury?