– Trevor May was unavailable — again — on Tuesday because of continuing back issues. And he is downright frustrated.

He last threw Sunday in the Twins victory over Detroit and felt good afterward. That changed as soon as he arrived in Cleveland, as his back gave him more trouble.

May, who has emerged as a key set-up man, has appeared in just four games since Sept. 9 because of a back condition that flared up when the Twins were in Tampa Bay just over a month ago. He has a knot on his lower right side that won’t allow him to pitch free and easy.

It has led to the daily ‘Is Trevor available,’ question. Most of the time lately, manager Paul Molitor has answered no.

“Not sure how it is going to respond here during the last week [of the season],” Molitor said. “I’m trying to stay optimistic. Day to day. Unfortunately there hasn’t been a lot of days here he has been available the last 10 days.”

May spoke to reporters on Tuesday while a Biowave machine was connected to his lower back, providing electric stimulus to the area. He goes out daily to play catch so he can gauge how his back is doing that day. He hopes to be able to walk into Molitor’s office and give him the thumbs up soon.

But he also wonders if he will be able to do that before the regular season ends.

“Me pitching and then going back down for five days isn’t good,” he said. “That isn’t going to cut it at this point. It’s frustrating. I never have problems with my arm. I feel like I can throw another 100 innings with my arm.”

It makes the roles Casey Fien and Glen Perkins even more important. Both bounced back from a rough game in Detroit on Friday to shut down the Indians in the late innings on Monday. And the Twins can’t afford to have Perkins suffer a setback with his neck and back, which game him problems last month.

“Everyone would like to have all their horses on board here in these situations,” Molitor said, “but when you don’t, you don’t. And people have to fill in and take care of those roles.”

Hughes hopeful

Righthander Phil Hughes, who was too ill to start Monday, played catch Tuesday afternoon and was encouraged.

He said he felt a little weak, but the session went well. Hughes’ appetite returned Tuesday and he can look forward to his next outing, whenever that will be.

He could be used out of the bullpen Wednesday, or he could throw a bullpen session Wednesday as preparation for a start Friday against the Royals at Target Field.

Molitor pointed out that Hughes could hold a bullpen session as late as Thursday and still be on line to start Saturday.

“We have not finalized any plans for him for the rest of the week or Saturday as of yet,” Molitor said.

Hughes threw five shutout innings last Wednesday against Cleveland. But Tommy Milone, who filled in for Hughes on Monday by giving up just two runs over 5⅔ innings, has given Molitor something to think about, too.

Whoever doesn’t start Saturday could be an option to start a tiebreaker game, if needed, on Monday — or start the wild card game if the Twins get that far.

Etc.

While Saturday’s starter is unknown, the other two matchups for the Twins-Royals series have been scheduled. On Friday, Ervin Santana will face righthander Chris Young. On Sunday, Kyle Gibson will face Johnny Cueto.

The FOX crew of Aaron Goldsmith, Tom Verducci and Ken Rosenthal will work Saturday’s Twins-Royals game, which has been moved to 12:05 p.m.