"He's one player who came into camp a little behind," Twins general manager Thad Levine said. "About eight to 10 days ago, he sustained a mild right oblique strain. Our training staff is calling it day to day right now. He's not throwing."
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Levine wasn't sure how Melotakis suffered the injury, but said it's not considered serious.
"We get the sense he's not significantly behind," Levine said. "The worst of this is behind him. He's been getting his treatment and is well on the road to recovery. But all that being said, he's not throwing yet."
Melotakis, 25, posted a 2.97 ERA with 42 strikeouts in 33 1/3 innings with Double-A Chattanooga last year. He missed the 2015 season after undergoing Tommy John surgery.
• Twins closer Glen Perkins, who is recovering from labrum surgery, is scheduled to throw his second bullpen on Saturday. He threw his first session on Tuesday without any issues. He'll continue to be monitored closely this camp.
• Twins position players don't have to report until Saturday, but only non-roster invitee Drew Stubbs has yet to show up at Hammond Stadium. Second baseman Brian Dozier and third baseman Miguel Sano both arrived for informal workouts on Friday.
• Special assistant Torii Hunter worked with the outfielders during informal drills, as they're not required to report until Saturday. Center fielder Danny Santana was impressive during short-hop drills, but Hunter joked with him by calling him a "cheater" because he was a former shortstop.
• The Twins have yet to schedule any "B" games this spring, but Twins manager Paul Molitor said it's likely because they have 31 pitchers in camp, including 11 who are expected to be stretched out to start.
• The Twins will host their annual open house at the CenturyLink Sports Complex on Sunday at 10 a.m. Fans will be able to watch the first full-squad workout. It'll also feature Healthfest 2017 with free blood pressure testing and free heart scans for children under 18.
Rhett Bollinger has covered the Twins for MLB.com since 2011. Read his blog, Bollinger Beat, follow him on Twitter @RhettBollinger and listen to his podcast. This story was not subject to the approval of Major League Baseball or its clubs.