The club and Nathan want to make sure what he's experiencing in his elbow is not due to anything more than the breaking up of scar tissue following his surgery. Nathan underwent surgery on Oct. 20 to remove bone spurs and loose bodies in the elbow.
"Everything is looking good as it not being super serious," Nathan said. "As far as tears or anything, it doesn't look like it's anything like that. That's a positive, and I'm going up there with positive thoughts.
"But we definitely want to be precautionary and make sure that we have all the information we could gather to at least give us peace of mind and know that hopefully nothing is going on."
Nathan was expected to fly back to Minnesota on Sunday night and have the tests completed on Monday. The Twins likely won't know the results until Tuesday.
The latest series of tests will be the same ones that Nathan underwent back in mid-September. The plan is to compare Monday's tests to the ones he had prior to his surgery and see if anything has changed.
"We have a very good complete set of tests that we did a few months ago," Twins general manager Bill Smith said. "That's why we want to fly him up there and have the exact same tests done by the exact same people. Then we'll have a much better idea."
The trip to Minnesota won't set Nathan back any further, as he was already expected to take a couple days off from throwing. The Twins are expected to be extra cautious with Nathan, not only based on his importance to the ballclub but also for the fact that this is Spring Training.
Until the club receives the test results, the timetable for Nathan's return to the mound is unclear.
There are four weeks remaining until Opening Day on April 5 in Anaheim, but Minnesota isn't ready to start thinking about whether this setback could prevent Nathan from being ready for the opener.
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"Until we know further, we're all optimistic that it's just scar tissue and we can move forward," Smith said. "We were going to give him a couple days anyway, so let's take advantage of it, send him up there, get the tests done and move forward."
Nathan is certainly a key component to the Twins' bullpen, and if he has to miss any time early in the season, it would be a significant blow to a team that has high expectations for the 2010 season.
The closer set a Twins single-season record with 47 saves in 2009, and he's recorded 36 or more saves in six consecutive seasons, making him only the second pitcher in big league history to accomplish the feat.
Manager Ron Gardenhire said it's too early for the Twins to start worrying about contingency plans if Nathan's out.
"If there was major concern, someone would have told me that," Gardenhire told the Minneapolis Star Tribune during the Twins' 15-5 split-squad loss against the Pirates in Bradenton, Fla. "They just want to make sure we're on the same path here. Get him checked out and we'll go from there."
Nathan said that despite the surgery, he felt he was ahead of schedule this spring prior to feeling the tightness in his elbow on Saturday. So his hope is that this will only be a minor setback.
"I think we always expect speed bumps when you are coming back from surgery," Nathan said. "It's nice that if there is a time to have it happen, it happened in my first game and not my last game down here. Now, we're staring at the season starting and me missing time during the season. I'm just going to hope it's as minor as it can be and hopefully it doesn't go into the regular season. ... But until we get the information and know exactly what's going on, I don't want to say anything [about a timetable] right now."