FORT MYERS, FLA. -- The Twins optioned infielder Tsuyoshi Nishioka to Class AAA Rochester this morning. Nishioka, who is on the second year of a three-year contract, was believed to be fighting for a utility infield spot on the Opening Day roster.

Nishioka, 27, batted .240 (6-for-25) in nine Grapefruit League games this spring. He had several defensive miscues early in camp.

"It's definitely tough to swallow, but it's not like I'm getting baseball taken away from me," Nishioka said, through translator Ryo Shinkawa. "I came from Japan to challenge in this country and I’m just going to not give up and look for an opportunity to be back up."

Nishioka was a Gold Glove winner and batting champion for the Chiba Lotte Marines in the Japanese Pacific League in 2010. The Twins invested $14.6 million to acquire him, including a $5.3 million posting fee.

Last year, Nishioka broke his leg in the Twins' sixth game of the season. He returned from the disabled list in mid-June, but struggled, batting .226 with a .278 on-base percentage.

Nishioka will make $3 million this year, even if he stays at Rochester.

Asked what General Manager Terry Ryan and Manager Ron Gardenhire told Nishioka to work on in Rochester, the infielder said, "To slow the game down and to be able to be back to my old self, how I was playing in Japan."

Besides Nishioka, the Twins also optioned reliever Carlos Gutierrez and outfielder Rene Tosoni to Rochester. The team re-assigned nine others to minor-league camp: pitchers Jason Bulger, Luis Perdomo, Daryl Thompson, Esmerling Vasquez and P.J. Walters; catchers Chris Herrmann and Dan Rohlfing; infielder Aaron Bates and outfielder Wilkin Ramirez.

The Twins now have 45 players on their spring training roster.