MIAMI, Fla. — With a few minutes left on the game clock in the NFC Divisional Playoff, the 49ers were up 27-10 over the Minnesota Vikings. Hosting the NFC Championship Game at Levi’s Stadium was a lock.

Defensive coordinator Robert Saleh wanted to lighten the load of his starting linemen and get the backups some reps. It was the first playoff game for the 49ers since 2013, but Saleh was feeling confident that the game was in the bag. Little did he know, Kyle Shanahan did not approve.

“I freaked out at Saleh when he tried to take the starters out in Green Bay, or was it Minnesota?” Shanahan said Tuesday. “Yeah, it was Minnesota when we were up like three scores with two minutes to go and I freaked out.

“And then I did the math and I thought it was alright, but you get some scars from that stuff.”

Shanahan still feels the effects of the Falcons’ collapse in Super Bowl LI when he was the offensive coordinator for the club. Blowing the infamous 28-3 lead left a traumatic mark on the 49ers coach that likely will never disappear.

“Everybody asks what I learned from that Super Bowl and everything,” Shanahan said. “I wish I could say there was some easy answer that would have fixed us not blowing that lead but you know, I go back and am hard on myself about everything.

“I know the plays I wish I would have called differently, especially the second-and-11 pass once we got down there that led to a sack, so I wish I called a run there, but that was about it.”

Shanahan will never take the foot off the gas again, especially when facing top quarterback, like Patriots Tom Brady. Shanahan felt similar pangs of stress in the NFC Championship Game with a 14-point lead on the Green Bay Packers knowing all too well what Aaron Rodgers is capable of.

[RELATED: Shanahan convinced Sherman to sign with 49ers over Lions]

The situation will be no different on Super Bowl Sunday against the speed of the Kansas City Chiefs' offense and the incredible talents of Patrick Mahomes, who quickly racked up 41 unanswered points on the Houston Texans in the divisional round after falling behind 24-0. Shanahan will want to keep the 49ers' starters on the field no matter what the scoreboard reads.

“You realize when playing against good teams and good quarterbacks that you can never relax.”

Programming note: NBC Sports Bay Area feeds your hunger for 49ers Super Bowl coverage with special editions of “49ers Central” all week (8 p.m. Wednesday, 8:30 p.m. Thursday, 9:30 p.m. Friday, and 3 p.m. Saturday).

Also tune in at 1 p.m. on Super Bowl Sunday for a two-hour special of "49ers Pregame Live" with Laura Britt, Donte Whitner, Jeff Garcia, Ian Williams, Kelli Johnson, Greg Papa and Grant Liffmann. That same crew will have all the postgame reaction on "49ers Postgame Live," starting immediately after the game.