MILWAUKEE - Twins catcher Joe Mauer is batting .186, and if that's not frustrating enough, he's getting ripped for his pitch selection behind the plate, too.

When manager Ron Gardenhire replaced starter Scott Baker with Jose Mijares in the seventh inning Friday, he assumed the lefthander would throw sliders to Brewers slugger Prince Fielder.

Mijares threw six fastballs.

Fielder, the National League's RBI leader, jumped on the last one for a two-out, two-run double that lifted the Brewers to a 4-3 victory at Miller Park, the Twins' third loss in a row.

"I don't know what was going on with Mauer," Mijares said after the Twins fell back to 10 games below .500. "He never put the sign for breaking ball. Never. Fastball, fastball, fastball. Fastball. Last pitch, I'd like to throw a breaking ball. He said fastball. OK."

Said Mauer: "It's easy to say that now. I thought that was his best chance. He threw a couple good fastballs before that, but if you look at the tape, he didn't mean to throw it right down the middle."

With two outs in the seventh inning, the Twins had a 3-2 lead, but Baker had thrown 97 pitches and the Brewers had runners on first and third.

Fielder has terrorized righthanders for 18 homers and 49 RBI this year. Mijares had held lefties to a .222 batting average.

He fell behind in the count 3-0, screaming in disgust after missing with the third pitch. Another ball would have loaded the bases, but Mijares came back with two strikes, then missed his target with another fastball.

Mauer set up on the outside part of the plate, and the pitch sailed on the inner half. Fielder drilled it to right field. Mauer said Mijares' slider wasn't sharp the last time he caught him.

"Now that I think I about it, if he throws that slider and misses, the bases are loaded," Mauer said. "But that means [two] runners in scoring position, too."

The on-deck hitter was Casey McGehee, who is batting .230.

Danny Valencia's three-run homer off Brewers starter Randy Wolf had given the Twins a 3-2 lead in the sixth inning.

After going 2-0 with a 0.53 ERA in his previous two starts, Baker missed a chance to get another victory. He was charged with four runs over 6 2/3 innings after giving up eight hits and matching his season high with four walks.

Gardenhire pulled Baker right after he got Ryan Braun to pop up for the second out.

"Of course it would have been nice to face Fielder, finish my own inning," Baker said. "But in my opinion, that's the right move."

Said Gardenhire: "[Fielder's] numbers are huge against righthanders. His numbers aren't bad against lefthanders either, but the power numbers are way different. And Baker was close to 100 pitches and you've got a lefthander for that reason.

"A lefthander's gotta come in and hopefully spin some pitches. If you just throw fastballs -- I could leave a righthander in to throw fastballs. That's the way I look at it."