– Already down two starting pitchers, the Twins are down a reliever this weekend, too.

Casey Fien said he felt a “bite” in the back of his pitching shoulder when he slipped on the wet mound throwing his first warm­up pitch at Detroit on Thursday, and the Twins are trying to avoid using him until the stiffness disappears.

“I got through the inning [Thursday], and then started some treatment,” Fien said. The feeling is stiffness, not pain, he said, adding: “Maybe it’s nothing, maybe it’s something. We’ll see.”

Fien played catch in the outfield Saturday, then had a long talk on the warning track with athletic trainer Dave Pruemer, pitching coach Neil Allen and bullpen coach Eddie Guardado.

“He’s doing a little better,” manager Paul Molitor said. “I think we might still be cautious.”

The Twins, who have lost Ricky Nolasco to elbow inflammation and Ervin Santana to an 80-game steroids suspension already this season, would like to avoid a disabled list stint for their 32-year-old setup man.

“We’re going to see if we can get by [without him] the next day or two,” General Manager Terry Ryan said. “We’re hoping it’ll take care of itself.”

The first of many

Torii Hunter was out of the lineup for the first time this season, though he entered the game in the eighth as a pinch hitter for Oswaldo Arcia, then stayed in to play the outfield.

Molitor said he intends to keep giving Hunter occasional days off, to keep him fresh for the end of the season. It’s a habit that former Tigers manager Jim Leyland started in 2013, Hunter said, and he believes it’s the reason he has kept his batting average near or above .300 even as he nears his 40th birthday July 18.

“We’re going to try to spread his days out, now and then,” Molitor said. “It’s not like he’s a DH — he’s playing a position. I really don’t have a set number [of games] in mind, but hopefully his health is good throughout the year and we can keep him fresh.”

Molitor said he might give Joe Mauer occasional days off, too, but Mauer might serve as designated hitter on the days he’s not at first base. “If Joe’s healthy, I want him to play,” Molitor said.

Etc.

• Major League Baseball imposed a “modest” fine on Hunter for his comments critical of umpire Joe West on Monday, Ryan said. Hunter, called out on a checked swing against Joe Nathan to end the game, said, “Joe West needs to do his job. And he didn’t do it well,” among other things, after the game.

• Australian lefthander Lewis Thorpe underwent elbow reconstruction surgery Friday in Minneapolis. The 19-year-old, who has struck out 179 batters in 157⅔ professional innings, will miss the entire 2015 season.

Trevor May was in uniform, having been called up to replace the injured Nolasco. May, who will face the Royals in the Twins home opener Monday, said he wasn’t surprised to be called up when he heard about Nolasco. “It’s funny that a lot of people say, ‘Be ready, be ready.’ Your job is the same everywhere, so why wouldn’t you be ready?” May said. “I knew I’d be up sooner or later. It just happened to be sooner.”

• The replay challenge system cost the Twins a baserunner Saturday. Jordan Schafer, after a single, stole second base in the fourth inning. But White Sox manager Robin Ventura challenged the call. Replays showed Schafer was tagged a split-second before grabbing second base, and umpire Bill Welke’s call was overturned. It’s the second challenge that has benefited the Twins’ opponent this season; in Detroit, Molitor’s challenge of a pickoff play at first base was unsuccessful.