Kansas City, Mo. ? Third baseman Mark Teahen, in the midst of a breakthrough season for the Kansas City Royals, will have shoulder surgery on Friday and miss the rest of the season.

The Royals said they had been discussing the possibility with their second-year third baseman for more than a month.

“The smart thing to do is shut it down now and make sure I’m ready for spring next year,” he said. “Hopefully, it’s just minimal and I’ll be good and ready to go. Worse-case scenario, this makes sure I’m ready for spring training.

“I wanted to try to get through the year, but it’s kind of stupid for me to try.”

Teahen is hitting .290 and leads the Royals with 18 home runs and 69 RBIs. The operation on his right shoulder will be performed Friday in Los Angeles by Dr. Lewis Yocum.

“It’s a hard decision because I’m playing well and the team is starting to come together,” Teahen said. “But ultimately, I think it’s the wisest decision for me and the organization.”

Manager Buddy Bell said the Royals would not bring up third baseman Alex Gordon from the minors. Gordon, their No. 1 choice in the 2005 amateur draft, is considered the team’s third baseman of the future.