– Brusdar Graterol was in the Twins clubhouse Sunday. So it was time to get to the bottom of things.

Did you really throw a fastball 103.8 miles per hour?

“Wow,” he said. “That was a surprise for me, too. When I threw it and I saw the board, it was like, ‘Oh my God, really?’ So I’m happy and ready.”

The righthander is the Twins’ top pitching prospect, and the team brought him up with a chance to win over the hearts of the coaching staff while proving he is ready to help out in what is expected to be the team’s first Division Series since 2010. He got his first taste of major league competition Sunday, when he pitched a scoreless ninth inning in an 8-3 victory over the Tigers, giving up two singles and striking out the first batter he faced.

Graterol gave up three runs over 5 ⅓ innings spanning four outings at Class AAA Rochester, with all the runs coming on a home run. His other eight outings since being activated from the injured list because of a shoulder impingement have been scoreless. That included two outings for the Twins’ Gulf Coast League rookie team, followed by three at Class AA Pensacola.

It was there where Graterol, during an appearance on Aug. 17, hit 103.8 mph on the radar gun.

Graterol, who turned 21 last week, already has been followed closely by Twins fans, for he represents the power arm the organization has struggled to develop. He also throws a slider, curve and changeup, with the slider his second-best pitch.

Normally a starter, he is working out of the bullpen because he is coming back from an injury that cost him more than two months. The Twins will spend the month evaluating him. “Obviously, he’s an exciting young arm,” manager Rocco Baldelli said.

Baldelli said he hoped to use Graterol in a lower-leverage situation, and he found one Sunday, when Graterol pitched with a five-run lead against the majors’ worst team. He got a double-play grounder to end the game after Detroit put runners on first and third with one out.

Graterol’s first pitch hit 99.6 mph. He averaged 98.5 mph on his 14 pitches — 10 for strikes.

“I’m not looking for the miles per hour. I’m looking for strikes, to throw strikes,” he said after the game. “That’s what’s important — to throw strikes.”

Graterol was called up Sunday, the first day major league rosters can expand to 40 players but also after the deadline to be on the playoff roster. But MLB allows for a player to be added to the postseason roster if he is replacing an injured player. So Graterol could be postseason-bound with a strong September.

The Twins also called up outfielder Ian Miller, righthanders Zack Littell and Kohl Stewart and lefthanders Devin Smeltzer and Lewis Thorpe, while catcher/infielder Willians Astudillo and outfielder LaMonte Wade Jr. were activated from the injured list.

Gibson to injured list

Righthander Kyle Gibson, who battled E. coli during the offseason following a mission trip to the Dominican Republic and Haiti, was placed on the injured list because of ulcerative colitis, which causes inflammation and ulcers in the digestive tract.

Gibson is down about 10 pounds and has had trouble sleeping because of the condition. In May, he visited the Cleveland Clinic for help. He has been in consultation with specialists there since, but the anti-inflammatory medication he has been taking hasn’t worked.

He said he has felt weak during his past three starts and realized he needed to try something different. He is taking stronger medication and will use the time off to try to get better rest.

“My guess is that there is a connection [to E. coli],” Gibson said, “so the hope is to take this anti-inflammatory and get the inflammation under control so I can kind of get back to normal and do a scope at the end of year and make sure there is nothing else going on.”

Buxton activated

The Twins also activated Byron Buxton from the IL — surprising because his sore left shoulder has not improved enough for him to swing a bat yet. But the Twins feel Buxton can help on defense and on the basepaths while the healing process continues. He took over in center field for the ninth inning Sunday.

“Buck wants to be an active part of what’s going on right now,” Baldelli said of Buxton, who had been out since Aug. 1. “We talk about his skill set and the things he can do. He does things that nobody else can do.”