Jimmy Garoppolo practices with his San Francisco team-mates ahead of Sunday's Super Bowl in MiamiJimmy Garoppolo practices with his San Francisco team-mates ahead of Sunday's Super Bowl in Miami (AFP Photo/Michael Reaves)
A fast learner, Garoppolo watched from the sidelines as Brady led the Patriots to Super Bowl wins in 2015 and 2017.
"I definitely learned a ton of things," Garoppolo said of his time as Brady's understudy.
"On the field, off the field, how he goes about his business, dealing with the media, everything.
"All those things I learned I apply to my game and how I am today. Whenever you get the opportunity to learn from a guy that successful, you take it."
Brady, bundled out of the playoffs in the first round this season, has already been in touch with his former protege.
"He shot me a text saying good luck and everything like that, and just go handle business," Garoppolo said. "Nothing too complicated, just 'Go Win'."
Had it not been for Brady's remarkable longevity, Garoppolo might have still been in New England with several more Super Bowl appearances under his belt.
But his status as Brady's heir apparent came to an abrupt end in 2017 when he was traded away to the 49ers in a move that shocked the NFL.
Patriots coach Bill Belichick was reportedly against the move, but was instructed by the team ownership to offload Garoppolo, who was increasingly desperate to play after making just two starts in three seasons.
Even so, the whirlwind nature of the deal to San Francisco caught Garoppolo off guard.
- Crash course -
"We'd just had a game in New England," Garoppolo said. "We were going into our bye week. And I'd taken a nap that Monday afternoon. I woke up to 150 texts and calls. Next thing I know 6am next morning I'm on a plane out west. It happened fast."
Another crash course awaited him in San Francisco, where he was required to absorb the 49ers offensive playbook -- usually well over 100 complex passing and running moves -- in a fortnight.
"It was a lot of hard work," Garoppolo said. "A lot of extra time with the quarterback coach."
Garoppolo soon found himself at home in San Francisco however, winning all five of his starts in 2017 to suggest the 49ers faith in him was well-placed.
But a season-ending knee injury in a clash against Kansas City in week three of the 2018 campaign wrecked his progress, and the 49ers finished bottom of the NFC West with a 4-12 record.
Even with his upbeat personality, Garoppolo admits his road to recovery was challenging.
"Just getting through the first couple of months and overcoming those mental hurdles was pretty difficult," Garoppolo told AFP.
"A year ago I was learning to run again. It's crazy what can happen in a year."
Garoppolo has returned with a vengeance this year, coolly leading the 49ers potent offense through the
His team-mates speak adoringly of the quarterback known simply as "Jimmy G".
"Guys love being around him," 49ers tackle Joe Staley said.
"He's very genuine. He's a salt-of-the-earth guy. The ultimate team player."
The Garoppolo takes all the praise in his stride.
When asked by a reporter if he ever stopped smiling, he shot back: "How can you not?"
Garoppolo believes his laidback personality helps bring the best out in his team-mates.
"I think as a quarterback there's a fine line between being THE guy, and being one of the guys," he says. "I try to go back and forth with that one and just let it happen naturally.
"But when we're loose and having fun I think that's when our team plays its best."