EUGENE, Ore. -- Clemson junior Brianna Rollins set a collegiate record in the 100-meter hurdles with a time of 12.47 seconds at the NCAA track and field championships Thursday.

Rollins set the wind-legal mark in her heat of the semifinals at Oregon's Hayward Field. The final in the event is set for Saturday.

''I didn't know I broke the record,'' she said, smiling after coming off the track. ''I just thought it was a good race.''

She broke the record of 12.48 set by USC's Ginnie Powell at the 2006 NCAA outdoor championships in Sacramento, Calif.

Her mark is also a world best this season.

Rollins said she skimmed one hurdle with her left knee. She'll go back and look at the film to see what she can improve for the final.

Asked if she might break her own record, she said: ''We'll see.''

Rollins set a championship meet record in the 60 hurdles earlier this year with a 7.79 for the NCAA indoor title.

In other early events Thursday, Arizona State junior Anna Jelmini won the discus with a throw of 190-1.

In the women's 200 meter semifinals, LSU senior Kimberlyn Duncan ran a wind-aided 22.15, the fourth-fastest NCAA time in all conditions.

''Even though it's not completely legal, I'll take it,'' Duncan said.

Duncan is wrapping up a stellar college career. Last year she won the Bowerman Award, the nation's top track and field honor.

She is the only athlete to win the 200 at both the NCAA indoor and outdoor championships in back-to-back years. She won the indoor 200 title earlier this year, so a victory in the finals on Saturday at Hayward Field would give her a three-peat.

Duncan also qualified for Friday's final in the 100.