He couldn't help but give his mentor trouble.
"You're sitting down? What's going on here?" asked Brooks, who always stands up for his pregame session.
"You're allowed," Karl responded. "After you win 1,000 games, you're allowed to sit down."
"I'll be standing up for a while," said Brooks, just finishing up his second full season as an NBA coach.
If not for Karl giving Brooks a chance to grow as an assistant, who knows if the two friends would be coaching against each other when the Nuggets and Thunder start their first-round playoff series Sunday in Oklahoma City?
Brooks was halfway through his second season as an NBA assistant when Karl was hired in January 2005 to take over the Nuggets. It didn't take long for Karl to recognize Brooks' skills and aspirations.
The two would have different clashes than others on the Denver staff, and Karl sensed Brooks wanted to be the one "to pull the trigger."
"From very early in my relationship, I knew Scotty wanted to be a head coach and he had the personality of a head coach," Karl said. "Assistant coaches, some assistants want to be assistants. Some assistants want to be head coaches.
"Scotty definitely wanted to be a head coach."
So, Karl let Brooks give it a try — to a certain extent. Instead of requiring him to keep stats on how many passes were deflected and how many shots were challenged, Karl offered Brooks the chance to look at the game as though he was the head coach.
"He did also say that I don't want to hear about it every timeout either," Brooks said after the Thunder's practice Friday. "Keep them to yourself, keep your suggestions to yourself, but look at the game as if you're coaching it. You would call a timeout, you would call this play, you would do this defensive scheme. That gave me an opportunity to really focus on taking advantage of those 48 minutes. When you're an assistant, you have other things that you have to worry about.
"He gave me freedom just to look at the game through a head coach's eyes, even though I didn't have the stress and the pressure he had at the time."
Brooks also got his first chance to take the reins in the NBA because of Karl. He filled in as Denver's coach when Karl served a pair of two-game suspensions during the 2005-06 season, their only full season together.
Brooks left Karl's staff after only 1½ seasons to take a job as Eric Musselman's top assistant in Sacramento. He saw it as an opportunity to grow as a coach and to be close to his family in central California.
Karl has let him know many times that he didn't approve.
"That was not my favorite decision of my career in Denver, but I understood," Karl said. "He's turned out to be, he's got to be one of the top young coaches in the NBA today."
Brooks took with him an appreciation of how Karl handled fighting prostate cancer while still coaching the Nuggets — he's since dealt with a second cancer diagnosis and his son also beating lymph node cancer — and how his boss could coach different styles of basketball and had an obvious love of being in the gym for practices, shootarounds and games.
"He has a love for the game and a love for his son, for his family," Brooks said. "He put himself a distant third."
After just one year in Sacramento, Brooks interviewed for Seattle's vacant head coaching position. He didn't get it, but landed on the staff and put himself in the mix to replace P.J. Carlesimo when he got fired soon after the team moved to Oklahoma City.
Brooks guided the Thunder to a 27-win improvement last season and won coach of the year. This season, they beat Denver for their first Northwest Division title since the relocation and the No. 4 seed in the Western Conference playoffs.
"Right now, I don't like Scotty," Karl said. "Scotty and (Thunder assistant) Rex (Kalamian) are really good coaches that we had here. My first couple years here, they were kind of like family. They helped me through that first year and came back and had a good second year. It was fun.
"I hope somewhere along the way, our interaction will help us and not them."
AP Sports Writer Arnie Stapleton in Denver contributed to this report.