Kenyan Moses Mosop shattered 30-year-old track records for the rarely run 25,000 and 30,000 metres at the Prefontaine Classic Diamond League meeting on Friday.
The 2005 world 10,000 metres bronze medallist took more than two minutes off the longer race record, running one hour, 26 minutes, 47.4 seconds.
He clocked one hour, 12 minutes and 25.4 seconds at the shorter distance.
The 25-year-old lapped all seven of his competitors at least twice in the 75-lap longer race.
Japan's Toshihiko Seko set both previous records at Christchurch in March 1981. He ran 1:13:55.8 for 25,000 metres and 1:29:18.8 for the longer race.
Both distances are recognised as official world records by the International Association of Athletics Federations.
The races were part of a distance carnival on the eve of the Prefontaine Classic's main events.
