DETROIT - Righthander Phil Hughes cruised into the seventh inning Tuesday night in command of a tough Tigers lineup. But he was pitching with a secret.

That secret came out after Victor Martinez hit a sacrifice fly to cut the Twins’ lead to one run. Despite having thrown only 75 pitches, Hughes had to leave the game because of shoulder fatigue he’s been pitching through in recent weeks.

He went to the dugout, where he had a clear view of the onslaught the Tigers laid on Twins relievers as all of his fine work was undone. Detroit scored all their runs in the seventh inning against a laboring bullpen to flatten the Twins 7-2.

The Twins were eyeing their third victory in four games. Now they have to avoid being swept in a series for the eighth time this season.

Hughes showed no weaknesses while on the mound. He got through the fifth and sixth innings with only nine pitches in each, and the Twins led 2-0 on solo homers by Joe Mauer in the fifth and Miguel Sano in the sixth.

When manager Paul Molitor emerged from the dugout in the seventh and spoke briefly with Hughes before taking the ball from him, it made no sense until after the game.

Hughes said his shoulder has improved and was never serious enough for him to go on the disabled list. Molitor and the coaches have been aware of it, and he warned them in the sixth inning to have the bullpen ready.

“I just said keep an eye on me because if there’s a drop in velocity, I’d rather have a fresh bullpen arm [rather] than me trying to get through [Miguel] Cabrera and [Victor] Martinez and [Nick] Castellanos in a tight situation like that with a lead,” Hughes said.

Cabrera led off the inning with a triple — just out of the reach of center fielder Danny Santana — and when Martinez flew out to deep center to cut the Twins’ lead to 2-1, it was a warning sign Molitor heeded.

“I was just trying to firm up a little bit that the right move was to get him out of there,” Molitor said, “and I think he agreed that was the right thing.”

Michael Tonkin (1-2) replaced Hughes and got one out. He gave up three hits, including an RBI single to Cameron Maybin that tied the score.

Trevor May replaced Tonkin and didn’t retire a batter. Jose Iglesias smoked a fastball that wasn’t high enough for a two-run single that gave Detroit a 4-2 lead. May then threw a hanging breaking ball that Ian Kinsler bashed it into the seats in left for a two-run homer. J.D. Martinez followed with a solo shot to right to give Detroit a 7-2 lead.

Three batters. Four pitches. Three runs.

“I’m out there trying everything I can to get a guy out and nothing happened,” said May, the anguish in his voice easily heard. “Coming out of the game was like … as you can tell, I’m still pretty livid about what’s happened. And it has happened to this whole team.

“When a guy goes and throws his heart out like Phil did, he needed this. We’ve got to pick him up.”

Hughes will remain in the rotation. He said his shoulder has been getting stronger with therapy between starts. But the developments Tuesday because of his precarious health led to the Twins’ 28th loss of the season.

“We have been in a really tough spot, not winning a lot of games,” Hughes said, “and to put us in position where we do have a chance to win a game and for it to unfold like that late is tough to watch.”