Kenya's world and Olympic champion Asbel Kiprop eased to a comfortable victory in the men's 3km event at the Great Edinburgh Cross Country race.
He clocked nine minutes, 20 seconds to beat Britain's Jonny Hay (9.25), with Ethiopia's Kenenisa Bekele well down.
Ireland's Fionnuala Britton won the women's 6km race in 21.32 ahead of Britain's Gemma Steel and Elle Baker.
"It is nice to feel strong and run like that," Britton told BBC Sport.
Kiprop beat fellow Kenyan Brimin Kipruto, who won Olympic gold in the 3,000m steeplechase, and Ethiopian legend Bekele, who both finished well down the field.
Bekele, who won gold in the 5,000m and 10,000m in Beijing in 2008, is regarded as the biggest rival to Britain's Mo Farah at the 2012 London Olympics but he struggled with the pace.
Kiprop, 22, said: "I expected a very tough competition from them.
"I am excited having won here today after being second last year."
Britton beat a quality field at Holyrood Park to win by an impressive 20 seconds.
The 27-year-old said: "It is a big event and I knew I was the person everyone would try to chase down so I knew I had to have a good race.
"Now I will look towards the track and the Olympics and look to get times in the 5km or 10km.
"I've been told I need to move up in distance so I will go get it now."
In the men's 8km race, Spain's Ayad Lamdassem won in a time of 25.44 from American Bobby Mack, who just edged out Belgium's Atelaw Bekele.
In the team standings, Great Britain and Northern Ireland finished ahead of the United States and a European Select team.