Mack followed by intercepting a pass that Kizer dumped over the middle while trying to avoid a sack by Roy Robertson-Harris.
Rodgers got sacked early in the second quarter and had to be helped up after clutching his left leg.
The Packers' worst nightmare appeared to be starting all over again.
They would play alongside leading tackler Blake Martinez in the Packers' base 3-4 defence.
The loss overshadowed an impressive performance by new Bears pass rusher Khalil Mack.
DeShone Kizer, who the Packers acquired via trade with the Cleveland Browns back in March, is the only other active quarterback on the roster.
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Now I don't expect Brady to all of a sudden forget how to play quarterback, but he will now be under a microscope. Instead, he says he remembers that he and the offense "had the opportunity to put the game away and we didn't".
Rodgers initially remained down on the field where he was attended to by trainers before walking gingerly off the field and entering the medical tent.
After the game, NBC's Michele Tafoya asked Rodgers how confident he was that he'd be ready to go against the Minnesota Vikings in Week 2. He brought the Green Bay Packers back with him.
Rodgers had ACL surgery on his left knee while in college.
Several members of the training staff surrounded Rodgers on the field.
"No, I'm planning on playing", Rodgers said.
Trubisky made a valiant effort, going 23-of-35 passing for 171 yards. He also ran for 32 yards on seven carries, including a 2-yard touchdown run in the first quarter.
And the Bears' offense, after getting off to a strong start that resulted in 10 points on its first two drives, managed this: Punt, turnover on downs, punt, field goal, punt, punt, field goal, fumble (on fourth down). We know they were watching.