First athletics world record falls as athletes praise fast Olympic track

• US mixed 4x400m relay team break world record in Paris
• Joshua Cheptegei wins 10,000m title in Olympic record
• Latest medal table | Live Paris schedule | Full results

The purple track billed as the fastest in history already has its first world record. On a day when Uganda's Joshua Cheptegei won the men's 10,000m title in an Olympic record and Team GB's Keely Hodgkinson and Josh Kerr made an almighty statement of intent, the US mixed 4x400m relay team broke the old best by more than a second.

Watching on was Jon Ridgeon, the World Athletics chief executive, who predicted that more records would tumble in the next eight days. The track is fast, really fast," he said. And the athletes are also coming here in sublime form. I wouldn't be surprisedif we saw four or five world records."