MINNEAPOLIS -- Joe Mauer was held out of the Twins' lineup against the Red Sox on Friday night because of back stiffness and is day to day.
Manager Ron Gardenhire said the injury isn't serious, as Mauer woke up with a sore back and the decision was made to keep him out for precautionary reasons. Ryan Doumit started at catcher in his place and hit fifth.
"It's pretty simple here -- he came in with a stiff back and there's no sense of him playing in this weather," Gardenhire said. "[The trainers] said to give him a day here and we'll go from there. I listen to what they say."
Earlier in the day, it was raining at the ballpark, and there is another threat of rain later in the evening.
Mauer has been on fire recently, as he's on a 14-game hit streak. He's batting .446 (25-for-56) with 11 doubles and 11 walks over that span to raise his batting average to .349 with a .431 on-base percentage.
He didn't take batting practice before Friday's game and his return for Saturday is still questionable.
"We're hoping this is short-term," Gardenhire said. "We're hoping he can play tomorrow."
Parmelee makes first appearance in two hole
MINNEAPOLIS -- Right fielder Chris Parmelee made his first start as the Twins' No. 2 hitter on Friday against the Red Sox and right-hander Clay Buchholz.
Parmelee took the two-hole behind leadoff hitter Brian Dozier with Joe Mauer being held out of the lineup with back stiffness. Manager Ron Gardenhire said he went with Parmelee because of his ability to see pitches. Parmelee ranks third on the team with 4.19 pitches seen per plate appearance behind Mauer (4.28) and Josh Willingham (4.25).
"He's not the prototype," Gardenhire said. "I'm not going to ask him to bunt or hit and run, but he can take pitches and is not afraid to see pitches. And if Dozier is on base, he can hook a ball through the hole, too."
Parmelee, who is hitting .204 with a .288 on-base percentage in 33 games, said he wasn't sure the last time he batted second, but estimated he hit in that spot twice in the Minors. Parmelee said he didn't plan to change his approach despite the move up in the lineup from his usual spot as the club's No. 7 hitter.
"My job today is to try and get on-base and knock in Dozier if he's on from the leadoff spot or any of the eight, nine guys," Parmelee said. "I'll just try to get on base for [Justin] Morneau and [Ryan] Doumit so they can try and knock me in."
Mastroianni to have left ankle surgery Wednesday
MINNEAPOLIS -- Outfielder Darin Mastroianni, on the 15-day disabled list with a left ankle stress reaction, will have surgery to repair a bone chip in his left ankle on Wednesday and is expected to be out at least six weeks.
Mastroianni has played in just eight games this year, as he initially injured his ankle on a foul tip in Spring Training on March 25. He reinjured his ankle early in the season while running and was placed on the disabled list on April 16.
The outfielder wore a walking boot for nearly a month before having it removed late last week, but Mastroianni still felt discomfort in his ankle so the decision was made to have surgery. Team physician Dr. John Steubs will perform the operation.
"The stress reaction has healed some, but not perfectly," assistant general manager Rob Antony said. "The bone chip doesn't affect some people, but with him, it was close to the ligament, or something to that effect."
Mastroianni could be moved to the 60-day disabled list if Minnesota needs to clear a spot on the 40-man roster, but the Twins haven't done that yet.
• The Twins released left-handed reliever Rafael Perez, who had shoulder surgery in September and signed with the club as a Minor League free agent on Feb. 14. Perez wasn't showing enough arm strength at Triple-A Rochester, so the Twins decided to cut ties. The 31-year-old posted a 2.25 ERA with two strikeouts and three walks in four innings with Rochester.
"It didn't look like he was going to be ready to come up here and help us," Antony said. "We just decided rather than continuing on with that, that we'd let him go and try to sign with someone else."
• Right-hander Tim Wood, who is on the 15-day disabled list with a right rotator cuff strain, had an MRI exam on his shoulder in Rochester, N.Y., on Wednesday. The initial prognosis was right biceps tendinitis, but team doctors took another look at Wood on Friday just to make sure and will know more on Saturday. Wood, who is out of Minor League options, had a 6.75 ERA in seven appearances with Triple-A Rochester on a rehab assignment before feeling the discomfort in his right biceps. He'll start a new rehab assignment once he's ready to pitch again.
• Right-hander Rich Harden's rehab from right shoulder surgery is coming along slowly. Harden, who signed a Minor League deal, threw batting practice this week and felt discomfort in his shoulder, said Antony.
"It's not going very well to be honest with you," Antony said. "We've backed him off a little bit and it's just a work in progress. We'll see where it goes from there."