"I'm just trying to stay positive," said Duchscherer, who threw 2 2/3 shutout innings before taking himself out Oakland's 3-2 victory. "They think I might just have irritation in the joint. Hopefully that's all it is."
To find out for sure, the A's are sending Duchscherer back to the Bay Area, where he'll be examined by team orthopedist John Frazier on Tuesday.
"I'm very concerned," Oakland skipper Bob Geren said. "It's obviously a big concern. He's our ace and our All-Star."
Duchscherer, who had a Major League-best opponents' batting average of .208 and the second-best ERA (2.59) in the American League entering Monday's game, had a similar issue last season. He was placed on the disabled list with a strained right hip in late May last year and had season-ending surgery in early June.
"From the day I had surgery, everything had gone absolutely perfectly until my last start," Duchscherer said.
The hip tightened on him early in a loss to Tampa Bay on Wednesday, but he pitched through it and went six innings. On Monday it bothered him during warmups and got progressively worse during the game, so he stepped off the mound after striking out Nick Punto in the bottom of the third and summoned Geren and head athletic trainer Steve Sayles.
After a brief conversation, Duchscherer was escorted off the field and replaced by righty Kirk Saarloos, who was recalled from Triple-A Sacramento before Monday's game.
"He called us out and said it's too painful," Geren said.
"I felt like I was gonna make it worse than it already was," Duchscherer added.
Duchscherer worked exclusively out of the A's bullpen from 2004-2007 but was moved into the starting rotation this spring in hopes that a more predictable workload would keep him healthier.
He suffered a strained right biceps in his first start of the season, however, and spent three weeks on the disabled list. If Duchscherer's most recent injury lands him on the DL, it will mark the 22nd time the A's have used the list, tying the Oakland record set in 1992 and matched last season.
"It's terrible," Ellis said. "Not just for the team, but for him personally. He's been having such an incredible year. When he's our starter, we're 100 percent sure we're going to win that game."
They still managed to win with only eight outs from their ace, though, and that's why the clubhouse wasn't exactly a morgue. Ellis' homer off Twins starter Nick Blackburn was Oakland's first on the first pitch of a game since Mark Kotsay did it on July 21, 2004, at Seattle.
"We haven't been scoring a lot of runs, period, so to put one up there that quick was nice," Ellis said. "Blackburn's around the plate a lot, so I was looking for something to hit right away."
The A's padded the lead in the fourth inning, when Kurt Suzuki followed a walk to Frank Thomas and a double by Jack Cust with a two-run single to center field.
Saarloos, meanwhile, seemed unfazed by the Twins, who entered the game tied atop the AL Central standings. He went 3 2/3 innings and allowed three hits while striking out three without a walk to pick up his first win for the green and gold since 2006.
"Saarloos came in and did just a super job against us -- changing speeds, his slider, his changeup. We didn't get much going," Twins manager Ron Gardenhire said. "You are trying to figure out how to hit [Duchscherer], and then you don't have him out there after he gets hurt, and then you have to make another adjustment. But their bullpen just did super."
The Twins cut the lead to one in the eighth. After a leadoff single by Denard Span off Huston Street, Joe Mauer split the outfielders with a drive to the wall in left-center field for a triple off Brad Ziegler and scored on the play when left fielder Eric Patterson's throw to third skipped into the Twins' dugout.
Ziegler then gave up a single to Justin Morneau before getting Jason Kubel to bounce into an inning-ending double play, and he shook off a two-out walk by striking out a demonstrably frustrated Brendan Harris to lock down his third save in three opportunities since wresting the role from Street.
"He's pretty nasty," Gardenhire said. "The last pitch to Harris, we went and watched it, it's on the black. It cut the outside corner of the plate, the tip of it, and that's pretty nasty.
"That's why the guy gets a lot of people out."