MINNEAPOLIS -- We'll skip the heresy. A rare poor outing by Minnesota Twins closer Joe Nathan doesn't register in the same magnitude as one from Mariano Rivera. But 1,000 miles from the East Coast spotlight, the affable Nathan has become nearly as reliable, if not as dominant, as any closer in the game.

So when Nathan, who entered a tie game in the ninth inning on Sunday, gave up back-to-back doubles to Tampa Bay's Akinori Iwamura and Dioner Navarro, the crowd of 27,024 at the Metrodome sat in stunned silence. The Devil Rays quickly added another run and beat Nathan and the Twins, 6-4, for Nathan's first loss since Sept. 6, 2005, to Texas.

"I know I'm not perfect," said Nathan, who had not allowed a run in five appearances this year. "I've gotten my brains beaten in plenty of times. I've just got to come back, work hard, and make some pitches."

The loss wasn't the only thing that made Twins manager Ron Gardenhire gloomy. During the game, he learned that third baseman Nick Punto, who sprained an ankle during batting practice on Saturday, will go for a magnetic resonance imaging (MRI) test on Monday and is probably bound for the disabled list. Punto will be the third veteran to go on the DL already, joining Jeff Cirillo (knee surgery) and Rondell White (right calf strain).

"We don't have a third baseman ready [in the Minors]," Gardenhire said. "It's not a good situation."

By rallying against Nathan, the Devil Rays salvaged a split of the four-game series. Brian Stokes earned the victory in relief of Jae Seo, with Al Reyes picking up his fourth save with a perfect ninth.

The Twins had scrambled back to tie the game at 4, and starter Boof Bonser was off the hook when Nathan came in for the ninth. Gardenhire doesn't usually use Nathan in tie games, but he didn't have much choice.

Jesse Crain (sore right shoulder) was still unavailable, Glen Perkins and Juan Rincon were tired, and Dennys Reyes and Matt Guerrier had already combined to pitch 2 2/3 innings of scoreless relief behind Bonser. Gardenhire said he was hoping for two innings, if necessary, out of Nathan, who last pitched Thursday night.

Instead, Iwamura and Navarro both pulled sliders into right for doubles, and Carlos Pena followed with an RBI single. Nathan had allowed six hits in five innings this year, but on Sunday four of his first five batters got hits.

"It is a surprise, because you're so accustomed [to him doing the job]," right fielder Michael Cuddyer said. "He can go out and dominate a ninth inning. But it happens. Sometimes teams hit good pitches, sometimes they don't miss, and today was one of those days."

Bonser, after a promising beginning, again was victimized by home runs. He shut out the Devil Rays on one hit for 4 2/3 innings before allowing Jonny Gomes' RBI single in the fifth, then sixth-inning homers by Brendan Harris and Delmon Young for three runs. Bonser tied his career high with eight strikeouts over 5 1/3 innings. But he has already allowed five homers in three starts; going back to last year, he has given up at least one homer in his last six starts.

"I felt like I was coasting pretty good," Bonser said. "Then the two homers happened, and that was pretty much it.

"I'm not out there throwing batting practice and trying to throw home runs. It's tough."

Minnesota tied the game in the seventh off Seo. Torii Hunter, wearing Jackie Robinson's No. 42 in honor of Jackie Robinson Day, made like Robinson with an acrobatic slide around Navarro's attempted tag to score on Jason Kubel's double. Kubel would score from third when Jason Bartlett beat out an infield hit to deep short with two out.

These are the kind of games the Twins have frequently pulled out in recent years, with Nathan finishing it up. Nathan's numbers in three-plus seasons since joining the Twins from the Giants in the notorious A.J. Pierzynski trade were Rivera-like before today: A 16-6 record, a 1.46 ERA, and 126 saves in 136 chances.

"With Nathan on the mound, you figure he's going to shut them out," Gardenhire said.

But things don't always work out as statistics suggest. Sunday was one of those days for Nathan.