"Everything is going well," Harrison said. "I haven't had any issues with the back. Everything has been feeling good."
Harrison, after winning 18 games in 2012, made just two starts last year before undergoing surgery for a herniated disk in his lower back. The left-hander needed a second surgery to correct the problem and also had an operation in September on his non-throwing shoulder.
So far everything points to Harrison being at full strength when pitchers and catchers report to Spring Training on Feb. 16. His comeback is critical for the Rangers, but even more so now that Derek Holland will miss the first half of the season after undergoing microfracture surgery on his left knee earlier this month.
"It's unfortunate what happened to Derek," Harrison said. "I know what it's like to get hurt. Hopefully, he gets back on the mound as soon as possible. As far as my situation, I've got to focus on what I've got to do, be healthy and go out and make every start this year. That's all I can do."
Holland was expected to be in a rotation that includes Harrison, Yu Darvish, Alexi Ogando and Martin Perez. With Holland sidelined, the Rangers are considering their options for a fifth starter.
Nick Tepesch was the club's fifth starter coming out of Spring Training last season -- going 4-6 with a 4.85 ERA in 16 starts before going on the disabled list with inflammation in his right elbow on July 7. He made just one start and two relief appearances in September. Tepesch is also attending the mini-camp.
The Rangers have also re-signed Colby Lewis to a Minor League contract in the hope that he is fully recovered from two years of injuries that included surgery on the flexor tendon in his right elbow, and another to address the chronic pain in his right hip. Lewis was 26-23 with a 4.06 ERA in 64 starts with the Rangers in 2010-11, when they went to two World Series, and 4-1 with a 2.34 ERA in eight postseason starts. But he hasn't pitched in the Major Leagues since July 18, 2012.
The Rangers are also considering the possibility of moving left-hander Robbie Ross or right-hander Tanner Scheppers from the bullpen to the rotation. Other long-shot candidates include star-crossed left-hander Michael Kirkman and non-roster right-hander Justin Germano.
The Rangers are also evaluating outside candidates and are fortunate that the free-agent starting pitching market has stalled because of Masahiro Tanaka. He is the right-handed superstar from Japan who has been posted by the Rakuten Golden Eagles and is being pursued by a number of Major League clubs.
Clubs have until Friday to sign Tanaka, although he is expected to make a decision before then. The Rangers have interest in Tanaka, but have not yet emerged as one of the leading contenders to sign him.
Once Tanaka signs, it should open up the market for other free-agent pitchers. Right-handers Ervin Santana, Matt Garza and Ubaldo Jimenez are considered at the top of the list, but right-handers Jerome Williams, Bronson Arroyo, Jason Hammel, Tommy Hanson, Aaron Harang and Jake Westbrook, along with left-handers Joe Saunders, Paul Malholm, Bruce Chen, Erik Bedard and Chris Capuano are all still unsigned.
The Rangers will likely add somebody before they go to Spring Training now that Holland is sidelined for at least three months. But the best news they could get this week are positive reports on Harrison, Tepesch and Lewis. That could go a long way in alleviating the new and growing concerns Texas has about its starting rotation.