DETROIT – There will be at least one fresh face among the September callups — a flame-throwing fresh face.

Brusdar Graterol, the top Twins pitching prospect and one of the better prospects in all of baseball, is expected to join the team Sunday. Graterol, who turned 21 Monday, has made three appearances for Class AAA Rochester since being promoted from Class AA Pensacola, giving up three runs over 5⅓ innings. A three-run homer Tuesday accounted for all of the runs scored. He struck out two Friday during a scoreless outing.

He was be part of a group of players from Rochester who traveled to Detroit on Saturday so they can be available Sunday. The group also includes righthander Zack Littell, catcher-infielder Willians Astudillo and outfielder Ian Miller. More players are expected to join after Rochester's season ends on Tuesday.

Both Graterol and Miller will have to be added to the 40-man roster so they can be eligible to play. The Twins currently have 39 spots filled on the roster, so they are expected to open up a spot by moving an injured player — righthander Sean Poppen is a possibility — to the 60-day injured list.

Graterol is a starting pitching prospect who is working his way back from a shoulder impingement that kept him away from game action for nearly 10 weeks. Before that, he was 5-0 with an 1.89 ERA for Class AA Pensacola.

After getting healthy, Graterol made two appearances for the Gulf Coast League rookie team and three for Pensacola before joining the Red Wings. Being at Rochester allowed him to get used to the same baseball that is being used in the majors.

Graterol can hit triple digits with his fastball. And during his last outing at Pensacola Aug. 17, the stadium scoreboard had one of his fastballs at 103.8 miles per hour. He also throws a good slider and is working on changing speeds.

The Twins feel Graterol can help them out of the bullpen the rest of the season, then he will likely build back to be a starter in 2020. Baseball America has Graterol ranked third behind Royce Lewis and Alex Kirilloff on its top-10 list of Twins prospects. MLB.com has him ranked as the 55th-best prospect overall.

Graterol has averaged 9.6 strikeouts per nine innings in his minor league career and has allowed just eight home runs in 213 innings. He was signed for $150,000 out of Venezuela in 2015.

Miller, 27, is a surprise promotion. The career minor leaguer was purchased from Seattle on Aug. 10 and batted .233 in 15 games with the Red Wings. But he has 35 stolen bases this season and has stolen 50 in a season before. So he will be the pinch runner deluxe late in games.

Gonzalez improving

Marwin Gonzalez said his abdominal pull is feeling better and that he hoped to be able to swing a bat soon. But the Twins have yet to schedule any sort of swinging session.

"Truthfully, I know he's doing better. I know he's feeling better," Twins manager Rocco Baldelli said. "We are not going to rush him. He could certainly takes some dry swings or things like that. He may even get on the field fairly soon. I don't have a firm timeline in my head. I'm not even sure if our training staff has a firm timeline for him."

Baby Gibson on way

Kyle Gibson will leave the team Thursday and fly to St. Louis, where his wife, Elizabeth, is expecting the couple's third child. He will return during the weekend series vs. Cleveland. The Gibsons met while students at the University of Missouri, and his wife has relatives in the St. Louis area.