Rhasidat Adeleke moved to 20th in the all-time list for the women's 400m as she won the National Collegiate Athletics Association (NCAA) title in the US after smashing her own Irish record by 0.34 seconds in Texas by triumphing in 49.20 seconds.
US star Britton Wilson was the strong favourite for the final but had to settle for second spot in 49.64. Adeleke's win saw her become the first Irish victor at the NCAAs since 2006.
Sligo athlete Mary Cullen's 5,000m triumph 17 years ago was the last time an Irish athlete had triumphed at the prestigious US collegiate championships. Wilson remains second in this year's world rankings behind Dominican Republic athlete Marileidy Paulino (48.98) but the American was unable to get close to her season's and personal best of 49.13 as she was overhauled by the Irishwoman in the closing 50 metres.
The American's hopes of achieving a historic 400m and 400m hurdles double at the championships unravelled as she later could only finish seventh over the barriers in a disappointing time of 55.92 - some 1.47secs behind winner Savannah Sutherland. Adeleke's win saw her become the first Irish sprinter to win a NCAA title and she also helped her University of Texas team clinch the 4x100m relay gold.
The Tallaght athlete said: "I just went out trusting myself. I'm not really sure what I went through the 200 in.
“I just put myself into position coming into the home stretch and it was the kick at the end, which is something I've been doing well all season." Adeleke's collegiate triumph adds further credibility to the belief that she will be among the medal contenders at this year's World Championships in August.
She was a semi-finalist in the 400m at last year's World Championships in Oregon and a month later went on to finish fifth over the distance at the European Championships in Munich. While Adeleke celebrated, there was disappointment for another Irish athlete, Sophie O'Sullivan, who finished 12th and last in the 1500m final in 4:22.81.
The daughter of legendary Irish athlete Sonia O'Sullivan was fastest qualifier in Thursday's heats after running 4:09.58 but was unable to reproduce that kind of form as she finished over 14 seconds behind Harvard's winner Maia Ramsden.