CHAPEL HILL, N.C. — North Carolina star Tyler Hansbrough is out of practice indefinitely with a stress reaction condition in his right shin.

The reigning Associated Press player of the year did not practice Thursday. Instead, he underwent an MRI that revealed the stress reaction, which if not properly treated could lead to a stress fracture, team spokesman Steve Kirschner said.

The school issued a statement saying there is no timetable for his return and no further information on the injury was available. Coach Roy Williams said he would have no comment until Friday after he meets with Hansbrough and the medical staff.

Hansbrough played in all 108 games during his previous three seasons at North Carolina, and has two weeks to heal before the Nov. 15 season opener against Pennsylvania if he is to keep that streak intact.

He is the first AP player of the year to return to school since LSU's Shaquille O'Neal in 1991, and probably the biggest name to skip the draft and play a fourth season in college since Tim Duncan returned to Wake Forest a decade ago.

Hansbrough averaged 22.6 points and 10.2 rebounds last season in leading North Carolina to a school-record 36 wins, its second straight Atlantic Coast Conference tournament title and its first Final Four since 2005.

He begins his senior season 122 points behind Phil Ford's 30-year-old school scoring record of 2,290 points, and is within reach of the ACC's scoring record of 2,769 set by Duke's J.J. Redick in 2006.