The Twins will not head into the regular season with their first-choice roster in place.

Manager Rocco Baldelli announced Wednesday that righthander Jake Odorizzi, slated to be the No. 2 starter in the rotation, will begin the season on the injured list because of upper back soreness. Odorizzi was scratched from his outing Monday because of the injury, and has not recovered sufficiently for him to take the ball Saturday against the White Sox.

So the Twins will start, in order, righthander Jose Berrios, lefthander Rich Hill and righthander Kenta Maeda in the three games against Chicago.

Odorizzi went 15-7 last season and was named to the All-Star team for the first time in his career. Baldelli said the IL move will be backdated so Odorizzi will only miss the first five games of the regular season.

“He’s dealing with a little something, but he’s still able to take part in most of his day and most of his preparation,” Baldelli said. “I wouldn’t expect this to linger too long. I would expect him to be back out on the mound sometime soon, probably throwing a bullpen either just before we come back or soon after we come off the road, and then be ready to go.”

While Odorizzi is out for the opening weekend, Byron Buxton could be in.

Buxton, who is recovering from a left midfoot sprain, worked out at CHS Field in St. Paul on Wednesday, getting some running in and facing live pitching. Buxton injured himself while changing directions as he attempted to catch a fly ball. The injury can be a serious one, but a day later, Buxton did not need protection and could put weight on the foot, a good sign. He might not be ready to play on Friday for Opening Day, but he could be available later in the series. He’s expected to drive to Chicago on Thursday.

The Twins have until 11 a.m. Thursday to set their 30-man roster for the season opener.

“Buck was able to go over to St. Paul, get a full day of work in, run and pick up the intensity on his running,” Baldelli said. “I got some videos of him getting swings off of live pitching. That’s what allows him to actually get a lot in and we’ve talked to Buck about potentially coming over this weekend.”

Three homers off Bailey

Homer Bailey at least got his work in.

The veteran righthander didn’t have the greatest line in a 4-3 loss Wednesday, after Cubs hitters barreled up a few of his pitches.

Anthony Rizzo blasted a two-run home run to right in the first inning on a split-fingered fastball throw belt-high and over the plate. Three batters later, Willson Contreras took a Bailey fastball to the opposite field for a solo home run and a 3-0 Cubs lead.

Bailey recovered to toss a scoreless second inning, but Contreras struck again in the third, driving a Bailey fastball over the center field wall, a blast measured by Statcast at 444 feet.

That ended up being Bailey’s final inning. He gave up four runs on five hits and two walks with three strikeouts. He was replaced by Tyler Clippard.

“Had a few that I kind of left up in the zone,” Bailey said. “It’s not hard to tell which ones they were, but consistently looked like [command] was slowly getting there.”

The Twins closed within 4-3, scoring on a passed ball, wild pitch and force out — real exciting stuff. The game ended with Nelson Cruz flying out to the warning track with a man on in the ninth.

Who leads off?

The game began with Mitch Garver leading off against Cubs lefthander John Lester, a reminder that Baldelli used him in that role 25 times. And Garver made the most of it, hitting 12 homers with a .706 slugging percentage.

Baldelli likes to keep his roster thoughts to himself, but he has several options for a leadoff hitter when some teams have trouble finding one hitter capable of starting things off.

Max Kepler will likely return to the leadoff role this season, after batting in the spot 105 times last season. What Baldelli has to factor in is whether he should mix in Luiz Arraez, who had a .399 on-base percentage last season, as well as Garver against lefties.

And Jorge Polanco could also bat leadoff if needed.

“We have guys that could fit in nicely almost anywhere you put them,” Baldelli said. “We can talk about strategy and we can talk about lineups and balance, and even balancing traits of hitters as opposed to just left-right balance. There are a lot of really interesting ways to get into it.”