DETROIT – Righthander P.J. Walters told the Rochester Democrat and Chronicle on Thursday that he is being promoted to the Twins and expects to start sometime this weekend.

Walters is 4-2 with a 3.31 ERA for the Red Wings. Indications are that Walters could start Saturday against the Tigers. Walters won his first game as a Twin, in his second start for the team, at Comerica Park on May 17, 2012.

The Twins weren't able to stretch out Walters in spring training, making it difficult for him to win a job in the rotation. After a couple rough outings early, Walters has thrown at least six innings in seven consecutive starts. He's pitched into the seventh inning six times.

In two moves this week, the Twins have called up Walters and righthander Samuel Deduno. Deduno arrived in Detroit on Thursday and will pitch Friday. Righthander Kyle Gibson, who has thrown complete-game shutouts in two of his past three starts, did not get the call.

Gibson is 3-5 with a 3.25 ERA in nine starts for the Red Wings, but he has sometimes followed good starts with poor ones. The Twins won't call up Gibson until he strings together good outings — or injuries on the major league staff force the Twins' hand.

And, even then, the Twins have one more option to call up in righthander Cole De Vries, who has recovered from a tight forearm and is pitching at Rochester.

High ERAs dropped

The demotions of Pedro Hernandez and Vance Worley took two of the majors' highest first-inning ERAs off the roster.

Worley's 11.70 first-inning ERA was seventh highest in the majors. Hernandez was tied for ninth at 10.50. Early runs have led to several roster transactions. Philip Humber led the majors in first-inning ERA, at 24.16, before being released by Houston. The Phillies' Roy Halladay (No. 3 on the list at 15.43), is out after having surgery. Rick Porcello (No. 4 at 14.85) started against the Twins on Thursday. Wade Le-Blanc (No. 5 at 12.86) has lost his spot in the Marlins rotation.

Colabello savors moment

Chris Colabello, who played in his first major league game Wednesday at age 29 years and 210 days, said the feeling of being in the big leagues is just sinking in.

"My phone has been going off the hook for the last 48 hours," he said. "It's been pretty amazing."

Friends and family are on their way, Colabello said. Lou, his father, and Silvana, his mother, will travel to Detroit this week for the series. Many friends also are expected from Massachusetts to see Colabello, who was born in Framingham and lives in Milford.

Colabello was not in the starting lineup Thursday, but he should get opportunities to play as Gardenhire searches for players to get his offense going. Colabello started in right field Wednesday, going 0-for-4 with two strikeouts.

Colabello is the fifth-oldest Twin to make a debut. The oldest, Minnie Mendoza, was 36 years, 144 days when he made his debut in 1970.

'Mastroscopic' surgery

Outfielder Darin Mastroianni underwent successful surgery on his left ankle Wednesday to remove a bone chip.

He will be in a cast for a week, then switch to a walking boot if he's made enough progress. The goal is for him to wear the boot for two weeks, check him again, then see if he can handle more physical activity as he works his way back to playing.

"[Doctors] were thrilled at the outcome," Twins assistant general manager Rob Antony said. "They were able to accomplished exactly what they wanted."

Etc.

• Justin Morneau was the designated hitter Thursday, getting a double in four at-bats, after getting hit in the leg Tuesday.

"He's pretty sore but he wants to play," Gardenhire said.

That allowed Chris Parmelee to start at first and Ryan Doumit to start in right field.

• Gardenhire said before the game that outfielder Oswaldo Arcia should be in the lineup Friday and that infielder Pedro Florimon could use a day off. Florimon only lasted 2½ innings at shortstop Thursday before spraining his right index finger on a slide and being replaced by Escobar.