Breaking a national record held by Raelene Boyle is no mean feat, so it's little surprise 17-year-old Leah O'Brien is still coming to terms with what she achieved earlier this week. O'Brien streaked to victory in the U18 girls 100m final at the Australian Junior Athletics Championships in Perth, running a time of 11.14 seconds. Her effort beat Boyle's U18 national mark of 11.20, which was set at the 1968 Olympics. At just 17, Boyle finished fourth in the 100m final and claimed a silver medal in the 200m at the Mexico City Games. Boyle won silver again four years later in the 100m and 200m at the Munich Olympics, only denied gold by East Germany's systematic doping program. Until Tuesday, her Australian U18 100m record had been out of reach for many well-credentialed challengers, standing for 57 years. Melinda Gainsford-Taylor, Sally Pearson and Torrie Lewis are among those who couldn't beat the time when they were in the same age group. What O'Brien managed this week isn't lost on the Perth high school student, who entered the final with the modest hope of setting a state record. "It honestly means so much because Raelene Boyle [was] such a phenomenal athlete," O'Brien told Thursday's media call at the WA Athletics Stadium. "I'm sure so many people know her and that record has gone down in history. "To break it after 57 years is so special to me, especially on a home track in Perth. "I'm still really in shock because I honestly didn't expect to run it." Adding to the magnitude of the performance, O'Brien now sits ninth on the U18 world all-time list. She is equal fourth — alongside Pearson — on the Australian all-time standings at the open level, only 0.04 shy of Lewis's national record. O'Brien will join Lewis in the women's 100m heats on Friday at the Australian Athletics Championships, also being held in Perth. She admits to admiring 20-year-old Lewis, although she isn't daunted about facing open-age athletes. "I'm pretty excited to get the race experience," said O'Brien, who is coached by Briaden Clarke "I don't have too high hopes racing in opens, obviously I've already done five runs. "My body is a bit more fatigued than the other girls and I'm not as fresh but I think my goal hopefully will be making the final or even if I don't, to have a good run in the semis. "I really look up to all the older girls."