Blackburn, who was scheduled to pitch on Wednesday against the Rays, has had issues in both knees throughout his professional career, but Gardenhire deemed it typical Spring Training soreness.
"He came in today with a little bit of a sore knee, which -- that's happened in Spring Training with running around and all that stuff -- which is normal," said Gardenhire, who still hasn't decided who will start Wednesday's game in Blackburn's place. "But we might have to skip him next time, make sure we get that calmed down."
Signed to a four-year, $14 million contract on March 7, Blackburn has given up just one run in seven innings through three spring appearances thus far, giving him a 1.29 ERA.
"During the season, he'll pitch with it," Gardenhire said. "During Spring Training, we'll back him off."
Joe Mauer, sidelined since taking a foul tip off his right shoulder on Thursday night, was on the field in Fort Myers, Fla., on Monday, and Gardenhire said he was "feeling good."
Justin Morneau and Jim Thome, battling general soreness related to a 2 1/2-hour bus ride each way for Saturday's game against the Phillies in Clearwater, Fla., stayed away from rigorous activity at Hammond Stadium and just did their everyday back work. Gardenhire said they're progressing fine.
Bench coach Steve Liddle was back with the Twins after being in the hospital since Thursday with what was diagnosed as erosive gastritis, an inflammation of the stomach lining.
Alden Gonzalez is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.