DES MOINES, Iowa (AFP) — Brianna Rollins served notice she is a force to be reckoned with by matching the fourth-fastest 100m hurdles time in history at the US Athletics Championships on Saturday.

Running in her first US outdoor nationals, Rollins booked a berth at the World Championships by posting a dominant victory over a quality field in a time of 12.26 seconds.

Only Bulgarian Yordanka Donkova, who set the world record of 12.21 in 1988, and compatriot Ginka Zagorcheva have run faster.

“I just feel so overwhelmed, so emotional,” Rollins said. “It is so amazing.”

The 21-year-old, who until turning professional this month was competing for Clemson University, improved on her own season-leading time of 12.39.

She ran under that in both the heats and semi-finals, but both times were wind-aided.

Rollins finally got a legal wind of 1.2 metres per second in the final and flew to an American record.

Queen Harrison was a distant second in 12.43 and Nia Ali claimed a third berth for the World Championships in Moscow on August 10-18 in 12.48.

Lolo Jones’ hard luck in big events continued. The hometown favourite, who endured disappointment at the 2008 and 2012 Olympics, was fifth.

Dawn Harper, who has a bye into the worlds as the Diamond League 100m hurdles winner last season, opted out of the semi-finals and final.

Rollins, whose best 100m hurdles time prior to this season was 12.70, has now established herself as a contender against the likes of Harper and world and Olympic champion Sally Pearson of Australia.

It’s heady stuff for an athlete who only took up running in high school “because someone told me I was fast”.

She opted for hurdles “because I thought it was interesting and fun to do”.

Rollins’ scintillating performance was one of three world-leading performances on Saturday.