A lot of things went the 49ers’ way in Sunday’s win over the Saints. One thing nearly went against them though in catastrophic fashion.

After a third-and-2 incompletion to George Kittle, head coach Kyle Shanahan and quarterback Jimmy Garoppolo had a miscommunication with the ensuing play call. The noise in a raucous Superdome caused Garoppolo to mishear the play and relay the wrong one to his offense.

Shanahan on Monday told reporters the typically rambunctious crowd was even louder than normal.

“The thing that impressed me the most was just how he handled the noise,” Shanahan said of his quarterback. “I’ve been in that stadium a lot, but it was louder than usual to me. You never can hear at the line, but it was very hard for him to hear in the huddle.”

Shanahan said the noise was the reason he asked for a timeout after the third-and-2 misfire to Kittle. He asked for play No. 14 on Garoppolo’s wristband, but the quarterback heard a play with No. 15. The result could’ve been disaster that ended the 49ers’ final drive.

“That’s why we had to call the timeout on that fourth-and-two, because I called a play that had 14 in it, but it sounded a heck of a lot like 15,” the head coach said. “Four and five, you know, and you just couldn’t hear it. That stuff was happening a lot and for him to just still keep his poise and try to fix things a lot in the game, he kept our guys pretty cool throughout the whole time.”

The differences in the plays could’ve been the difference between a win and loss for the 49ers. Shanahan explained Nos. 14 and 15 are different enough that he noticed something was amiss when the offense initially lined up for the play.

“Yes. I didn’t know what he had missed because I didn’t know exactly what 15 looked like at the time, but I knew it didn’t look like 14 when they lined up,” Shanahan said. “Fortunately, we had a timeout and we did it and fortunately the next play was a good play.”

The next play Garoppolo hit Kittle on a quick out that the tight end turned upfield for a 39-yard gain. A facemask penalty put the 49ers at the Saints’ 14-yard-line. They kicked a game-winning 30-yard field goal three plays later.

San Francisco handled the noise well, but it nearly came back to bite them. The good news is the win put the 49ers in a good spot to clinch home-field advantage. If they secure that, they won’t go back to the Superdome for the playoffs. Avoiding that noise in a postseason game could mean avoiding a game-deciding communication blunder.