Before the 49ers met the Chiefs in mid-August in a Super Bowl rematch that was the opposite of their February 2020 meeting in terms of importance, offensive coordinator Mike McDaniel had a message for rookie quarterback Trey Lance: "I'm excited for you to fail."

The former North Dakota State quarterback didn't love it.

"He kind of gave me crap about that," McDaniel said Thursday, "because he was like, 'Dang.' "

McDaniel, of course, meant no harm. Rather, he meant he was eager for Lance to start his NFL education by playing in the preseason opener and enduring his inevitable initial failures: Getting the type of experience that can only be gained from playing in games.

Now, nearly two months later, the games count, the stakes are significant for a Week 5 meeting and the 49ers are being forced to give Lance, 21, his first career start Sunday when they visit the Cardinals (4-0) at State Farm Stadium. With a loss against the NFL's lone unbeaten team, it will start getting late early when it comes to winning the NFC West title.

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McDaniel may no longer be as excited for Lance to fail.

However, that's probably unavoidable. Head coach Kyle Shanahan has made it clear he doesn't think Lance is fully ready for this moment by inserting Lance for seven snaps in 3 1/2 games before Jimmy Garoppolo, in the midst of a solid-and-unspectacular season, sustained a calf injury last weekend. In relief of Garoppolo, Lance looked like a QB who recently reached legal drinking age and threw 318 passes at North Dakota State.

Hall of Famer Steve Young saw himself in Lance during the second half of the 28-21 loss to the Seahawks. But it was the Buccaneers version of himself. That came before Young was traded to the 49ers and developed into a surgical pocket passer who could also makes plays with his legs, his primary weapon in his first two untamed seasons in Tampa Bay.

Young said Lance isn't currently "good enough" because he's so raw. But added this: "It's awesomely raw." He noted not being ready doesn't make a QB incapable of making plays. Lance's first extended NFL action was messy. He looked allergic to dropping back, surveying the field and delivering, but Young related to how Lance used his athleticism and competitive fury to make it look like a thing of beauty on the stat sheet: two touchdown passes, a 117.1 passer rating, 41 rushing yards and 5.9 yards per carry.

"Right now, obviously, there's still some concern," Young said on KNBR. "And you can see it in the play. You can see why there's some concern. The ball's flying around. It's like 5 feet over someone on a slant. It's chaotic. But because it's familiar to me — I don't know if it's going to work out like me — (but) when I watched him I was like, 'Hey, that is something I can build off of.' " How will this go? The 49ers are clearly buckling up for a wild ride.

"You know," McDaniel said, "that there are going to be some hiccups along the road."

Said Shanahan of the QB who has thrown 659 passes (33 more than Atlanta's Matt Ryan had in 2020) since high school: "He'll see some things out there that he's never seen before."

And Lance's teammates realize they might be required to step up with a starting QB who will almost certainly have down moments. The difficulty of Lance's task was compounded Saturday when All-Pro tight end George Kittle (calf) was placed on injured reserve.

"Hopefully we can kind of rally around him if we need to," Pro Bowl left tackle Trent Williams said. "And make his job a little easier on him."

Lance's first start is filled with excitement and anticipation because the possibilities — from an afternoon of errors to a coming-of-age performance — appear limitless. The situation smacks of 2012 when another young, unrefined, mobile QB — Colin Kaepernick, in his second season — was shoved into his first start in place of injured starter Alex Smith. Kaepernick had also looked choppy the previous week in relief of Smith, but he put on a passing clinic in a 32-7 dismantling of the Bears.

After the game, coach Jim Harbaugh still appeared stunned, as if he'd spent four quarters watching the ghost of Sammy Baugh, as he spoke glowingly of Kaepernick's unexpected performance.

Of course, Kaepernick was so good that season that he never let go of Smith's starting job. And Lance can create a similar situation if he dazzles Sunday in the desert. Even a loss, which would drop the 49ers to 2-3, could move Shanahan closer to starting Lance with an eye toward 2022."Jimmy's so much more polished," Young said. "And the idea of getting to the Super Bowl right now would feel like — Jimmy's the best bet because he's more polished. But you can feel the power, and the athleticism and the opportunity with Trey. You can feel it. And you want to see more of it."

Eric Branch covers the 49ers for The San Francisco Chronicle. Email: ebranch@sfchronicle.com Twitter: @Eric_Branch. The San Francisco Chronicle — www.sfchronicle.com — is distributed by Tribune Content Agency, LLC.