After rain delayed the game's first pitch for 1 hour, 21 minutes, Minnesota jumped on Clay Buchholz (2-6) for three doubles and two runs in the first.
That was enough support for Pelfrey (4-1), who retired the last seven batters he faced and lowered his ERA to 2.77. Pelfrey allowed five hits and struck out four to reward manager Paul Molitor for sticking with him.
"I don't think anybody likes seeing the bullpen going, especially not in the fifth," Pelfrey said. "But it worked out."
"It got a little dicey there," Molitor said.
The All-Star left-hander stayed in and worked a perfect ninth for his 17th save in as many chances.
"I would like to think our approach can be a little more concerted, a little bit more concentrated," Boston manager John Farrell said. "You never want to take away credit from a guy who has thrown the ball well this year in Pelfrey, but still I think we're capable of more than what we showed here tonight."
After Pelfrey struck out Ramirez in the fourth, Ramirez whacked the bench in the dugout with his bat. In the sixth, half of Ramirez's bat went flying into the stands after it broke on a soft liner to shortstop.
Buchholz settled down after the first and lasted 7 1/3 innings to notch Boston's 10th quality start in 13 games.
The Twins have won 18 of their last 24 games and 11 of 13 at home. Their 17 wins in May are the most in the American League and most for the month of May since they won 16 in 2011.
After injuries and ineffectiveness nearly cost Pelfrey a spot in the rotation out of spring training, the right-hander has been a big part of Minnesota's turnaround. Tuesday's start showed that Pelfrey, like the Twins, can pull through, even if things aren't going his way early.
"Like a lot of guys have been doing in that rotation, they find another gear," Molitor said.
ORTIZ DROPPED TO 5TH
Ortiz doubled in the first to end an 0-for-16 slump. Farrell dropped Ortiz to fifth in the batter order, the lowest spot in the lineup he's hit since May 6, 2012. Ramirez was moved up to the fourth spot and Pablo Sandoval hit third.
"Those guys have every ability to be an elite three guys in the lineup, and we're trying to gain a little bit more production and consistency," Farrell said.
With the 2016 Ryder Cup being held at Hazeltine National Golf Club, the Ryder Cup trophy was on display inside the Twins' clubhouse before the game. Several players, including 1B Joe Mauer, took pictures with it.
CF Aaron Hicks, a top amateur golfer in California before picking baseball, was a little more hesitant, choosing instead to admire the trophy from a distance.
Twins: In his second rehab outing at Triple-A Rochester as he recovers from a shoulder injury, reliever Casey Fien needed just 10 pitches to get through a scoreless inning.
Both teams will be back on the field at noon on Wednesday to wrap up the three-game series. Twins RHP Phil Hughes (3-4, 4.50) will be trying for his third straight quality start. RHP Rick Porcello (4-3, 5.07) goes for Boston and is 5-1 with a 2.96 ERA in his last eight starts at Minnesota.
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