COLUMBIA, Mo. (AP) — Michael Porter Jr. insisted before the season that he was not necessarily a one-and-done player who would leave next year for the riches of the NBA.

The standout Missouri freshman will have plenty of downtime to consider his future after the school announced Tuesday that he would miss the rest of the season following lower back surgery. The procedure, called a microdiscetomy, was scheduled in Dallas and the expected recovery time is three to four months.

The injury is a staggering blow for last year's top high school recruit, just as it is for a Missouri program excited for the future following his arrival and the talented recruiting class that followed him to Columbia.

"I cannot wait to be completely healthy and playing the game I love, once again," Porter said.

Porter signed with Missouri after originally being committed to Washington, doing so after former Huskies coach Lorenzo Romar was fired in March. His father, Michael Porter Sr., was an assistant coach at Washington at the time and was later hired by first-year Missouri coach Cuonzo Martin.

The 6-foot-10 freshman averaged 36.2 points and 13.6 rebounds per game as a senior in high school, and he was a McDonald's All-American. He showed how that potential might translate to the college game in an exhibition game against No. 3 Kansas before the season, scoring 21 points in 23 minutes — and he was chosen as the co-Southeastern Conference preseason Player of the Year.

He played only two minutes of Missouri's season-opening win over Iowa State before missing the last three games with the injury. The school said the surgery would involve two discs in his back, and that he's expected to make a complete recovery.

"Our top priority as a program is the well-being of our student-athletes, so Michael beginning this process to be 100 percent healthy is important to all of us," Martin said. "Our focus has been on Michael's well-being, just like every other player in our locker room."

Porter talked openly before the season about the possibility of leaving college after one season. He said it was important for him to leave a "legacy" at Missouri, because "the money will be there whenever I decide to leave."

"But if for some reason it goes wrong and we don't do as well as we expect, I would highly consider coming back for a second year," he said at the time.

___

More AP college basketball: http://collegebasketball.ap.org and http://www.twitter.com/AP_Top25