EAGAN, Minn. — Vikings Head Coach Mike Zimmer on Monday did not reveal who will be the starting center Sunday against San Francisco.

But Minnesota has a handful of options going forward.

Pat Elflein, who started 14 games as a rookie in 2017, was recently cleared to return to practice after being on the PUP list for all of training camp. Elflein, who made the 2017 PFWA All-Rookie Team, was a third-round selection in 2017.

If Elflein isn't able to go, the Vikings could turn to Brett Jones or Danny isidora.

Minnesota acquired Jones in a trade with the Giants last week. The lineman stepped in and played both center and guard in the preseason finale against the Titans, playing 62 of 70 offensive snaps while impressing Zimmer

"I thought he did good," Zimmer said. "He's a good pass protector.

"I thought he did a nice job when they had the power runs, the double teams and things like that. I thought he did a good job with those," Zimmer added. "For coming in in one day and playing, that's impressive."

Isidora was a fifth-round pick in 2017 and made one start as a rookie. While he primarily played guard during his career so far, Isidora also spent time at guard and center against Tennessee.

Zimmer said Isidora has come "really far" since taking on the position in recent weeks.

"I think that might be a natural position for him," Zimmer said. "And for him to do it in basically a week, I thought it's been impressive. It's been good this week as well."

Here are four other takeaways from Zimmer's podium session Monday:

1. Double dose

It seemed Mike Boone and Roc Thomas were battling each other for the third running back spot throughout training camp and the preseason.

It turns out both rookies did enough to make the team.

The Vikings kept both undrafted free agents on the roster over the weekend, bringing plenty of depth to a group that includes running backs Dalvin Cook and Latavius Murray and fullback C.J. Ham.

"I thought both of them have a chance to be good players," Zimmer explained about why both were kept on the roster.

The duo combined for 478 total yards from scrimmage in preseason play.

Boone had 283 total yards (195 rushing and 88 receiving) while Thomas had 195 combined yards (66 rushing and 129 receiving) in preseason action.

2. Meet the new punter

Minnesota shuffled up its special teams group Sunday as the team added punter Matt Wile and released Ryan Quigley.

The 26-year-old punted eight times for 392 yards (49.0 average) with a long of 58 for the Steelers in the preseason. He and the coverage team had a net average of 48.8 and placed four punts inside the 20-yard line without having a touchback.

"He had a good preseason," Zimmer said. "He didn't punt today [at practice], but he did a nice job holding, so we'll see.

"His hang time was really good, his average was good [in the preseason]," Zimmer added. "We just didn't feel like we were punting very well in the preseason."

Wile has appeared in four NFL games, totaling 553 yards on 12 punts with a long of 59 and an average of 46.1.

Zimmer said Wile could be a candidate on kickoffs along with rookie kicker Daniel Carlson.

3. Welcome to Week 1

The slate has been wiped clean.

Minnesota begin its 58th season in franchise history Sunday by hosting the 49ers. The 2018 season kicks off at noon (CT) at U.S. Bank Stadium.

Zimmer said while there is excitement around this time of year, there is also a sense of uncertainty.

"It's different because you don't really know what they're going to do, you don't know how you're going to perform," Zimmer said. "Every year is a new year, every team is a new team.

"The chemistry of the team and the chemistry of your offense and defense may not be where you want it, so it's always a work in progress," Zimmer added.

The last time Minnesota and San Francisco met, it was in the 2015 season opener. The Vikings fell 20-3 on ESPN's Monday Night Football.

4. Diving into the depth

The Vikings have 53 players on their roster heading into Week 1 after having 90 players on the team after the preseason finale.

Minnesota kept 25 offensive players (three quarterbacks, five running backs, five wide receivers, three tight ends and nine linemen), 25 defensive players (nine linemen, five linebackers and 11 defensive backs) and three specialists.

Zimmer was asked if he liked how the 53-man roster panned out.

"You know, in some places you always feel like you're thin," Zimmer said. "But for the most part, I feel like we have good depth."