European Junior champion Stephanie Twell won the women's race at Saturday's IAAF Antrim International Cross Country meeting at Greenmount.
Aldershot's Twell won the 5,600m race with Ireland's Deirdre Byrne second.
Ethiopian Imane Merga won the men's event over 10k after pre-race favourite Boniface Kiprop of Uganda fell.
Kiprop, who won the Commonwealth 10,000m in 2006, had to settle for runners-up slot with Scotland's Andrew Lemoncello taking third.
Twenty-year-old Merga outpaced outpacing Kiprop by two seconds with a time of 24 minutes 32 seconds.
Twell, who had won clinched her third junior European title three weeks earlier in Brussels, seemed to have sewn the race up when opening a gap of 20 metres on the final lap.
But then Byrne, with the finish tape in sight, got back into contention, coming on to the world junior 1500m gold medallist's shoulder and fighting her determinedly to the line.
Twell, 19, kept her head to power away and win by a second in a time of 18 minutes 25 seconds with Freya Murray of Scotland finishing third in 18 minutes 32 seconds.
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