SANTA CLARA, Calif. -- The San Francisco 49ers haven't asked quarterback Jimmy Garoppolo to throw much this season, but they've consistently asked him to throw when it matters most: on third down.

More often than not, Garoppolo has delivered.

"That's usually where quarterbacks earn their money," 49ers coach Kyle Shanahan said. "You can do a lot of things on first and second down. You can mix in run or pass to even out the game, but on third down, that pass rush is coming. They always have their best coverages and blitzes called. You need a good guy back there."

Through eight games, not many teams have a better guy than Garoppolo back there when it comes to third down. Garoppolo is 47-of-65 for 494 yards, four touchdowns and one interception for a passer rating of 108.1 on third down. His completion percentage ranks second in the NFL, his passer rating is sixth, and his touchdown-to-interception ratio is tied for eighth.

Of those 47 completions, 36 have gone for first downs or touchdowns, which is the highest percentage in the NFL. All of it adds up to a third-down QBR of 89.6, which ranks behind only that of Kansas City's Patrick Mahomes.

With Garoppolo spearheading the charge on third down, the 49ers have converted 53 of 109 third-down chances, or 48.6%, which is fourth in the NFL.

The key to Garoppolo's success on the "money" down? Teammates say it's his ability to stay calm under pressure.

"He's a guy who is the same all the time," guard Mike Person said. "He's level-headed, even-keeled, and I don't think I've ever seen him fazed. He's just going to go out there and compete. He's knows his stuff, and he's just going to execute."

Take last week's game against Arizona. With the Cardinals loading up to stop the Niners' run game, Shanahan turned the offense over to Garoppolo.

Time and again, Garoppolo found a way to deliver in situations that weren't favorable. Third-and-6? A 9-yard completion to running back Tevin Coleman. Third-and-4? A perfectly placed pass to Emmanuel Sanders for a gain of 22. Third-and-7 just a few plays later? Another dime to receiver Dante Pettis for a 21-yard touchdown.

The throw to Sanders drew plenty of attention, including from Hall of Fame quarterback Peyton Manning. Breaking down the play on the latest episode of his ESPN+ show Detail, Manning said it was hard to believe Garoppolo and Sanders' timing is so good, so soon. "This is just an awesome throw," Manning said. "This is a throw that I'm not even sure Montana was making to Rice, Steve Young was making to Rice ... you cannot find a better throw as far as timing than Garoppolo to Emmanuel right here on this corner route. This is awesome stuff."

With the Niners clinging to a three-point lead and facing third-and-11 from their 25? A 16-yard strike to Sanders followed by a quick scramble and dump-off to tight end Ross Dwelley for 11 yards and a first down to clinch the victory.

By the time it was all said and done, Garoppolo was 13-of-15 for 160 yards with four touchdowns and no interceptions on third and fourth downs against Arizona.

"It was a pretty good feeling," Garoppolo said. "All those third downs at the end there, they were all pretty big. It's our job as an offense, when we get the ball like that with five minutes or so left, we keep the ball for the rest of the game. That's how you win football games."

This season, Garoppolo's 90.4 QBR on third down in the fourth quarter ranks fifth in the NFL. That might seem like an obscure statistic, but keeping drives alive to help put games away is a trait the 49ers figure to need as the season goes on, the schedule gets tougher and games become more important.

Just how often the 49ers will ask Garoppolo to carry the load remains to be seen. How he performs in those situations against better opponents does, too. But there's little doubt that the Niners trust him to make things happen when the game is on the line.

"He does what he always does," tight end George Kittle said. "The consistency that I see every single day. Whether it's our Thursday third-down practice, whatever it is, he's always locked in. He's always ready to go. He's one of the most professional people I've ever been around. He practices enough the stuff that he puts in. It allows him to make those plays."