The San Francisco 49ers face the Denver Broncos in their second preseason game on Monday, when Jimmy Garoppolo will play in a game for the first time since tearing his ACL in September.

That injury derailed a season previously filled with hope, but with Garoppolo back, there is again excitement around a team many expect to compete for the playoffs in 2019.

San Francisco still faces plenty of question marks on its roster. After a pair of practices with Denver, the Niners will hope the second exhibition game will help them find the answers to some of those burning issues.

Here we look at the three biggest questions around the 49ers ahead of their meeting with Denver.

Which Garoppolo will we see?

Garoppolo created headlines for the wrong reasons in the 49ers' final practice before they flew out to Denver, throwing five straight interceptions.

It is easy to put too much stock in practice performances, but days like the one Garoppolo endured on Wednesday naturally raise concerns about a quarterback who has not played a competitive game since September.

Other than that disappointing display, Garoppolo has been mostly solid in camp. He provided further evidence that his five-pick showing was an anomaly by bouncing back in the Niners' first joint practice with the Broncos. He hit his first eight passes in 11-on-11 drills before finishing 9-14 with a pick.

Kyle Shanahan believes there is more value in practice than preseason games. However, for the wider NFL world, how Garoppolo performs in his cameo on Monday will provide the first indication of whether he can recapture his 2017 best.

Who will step up on the offensive line?

Garoppolo is known for having a rapid release, though he got a bit gun-shy in a spotty start to last season before his injury.

It will be a necessity for him to get the ball out quickly if an offensive line hampered by numerous injuries is not up to scratch.

Center Weston Richburg is battling to be ready for Week 1 — with Ben Garland deputizing in his absence — following offseason knee and quadriceps surgery.

Swing tackle Shon Coleman's season is over after he sustained a broken fibula and dislocated ankle.

At guard, Mike Person was seen in a walking boot and on crutches after the first joint practice, though his injury is not severe. Joshua Garnett, his backup, is still recovering from finger surgery.

The 49ers need to find a replacement swing tackle and could use extra insurance at guard. With the starters unlikely to play significant snaps, the reserves at those positions have an opportunity to prove they are worthy of stepping up and filling the void against a talented Broncos front.

Can Tarvarius Moore lockdown the free safety job?

Jimmie Ward's extended spell on the sideline with a collarbone injury has opened the door at free safety for Tarvarius Moore. The former third-round pick has taken full advantage of the opportunity to the point where he could be named the starter at the position.

Ward had been expected to start at one of the most critical spots on the Niners' defense, but Moore, who played cornerback as a rookie in 2018, has enjoyed a superb camp at his college position.

His pick-six of Joe Flacco on Friday marked his third interception in two practices. Afterward, defensive coordinator Robert Saleh — per Matt Barrows of The Athletic — conceded Moore is making the decision at the position a tough one.

“It's definitely something to talk about,” Saleh said of the possibility of Moore starting.

“We always talk about; if you get your foot in the door, it's your job to blow that thing wide open. And he's doing a good job. He’s going to make it very difficult.”

Ward is edging closer to his return but won't be back in time to face the Broncos. Moore has the athletic ability, ball skills, and instincts to be a star in the secondary. If he shines again, this position battle could be decided.