GAA stars Bernard Brogan and Joe Canning and Ireland rugby star Simon Zebo will be among those running in Dun Laoighaire as the Wings for Life World Run comes to Ireland.
At 11am thousands start running simultaneously in 35 locations on six continents.
Athletes of all shapes and sizes – from part-time joggers to professional athletes and ultra runners – compete to stay ahead of the Catcher Car, the finish line that chases the runners – a ground breaking format.
The Catcher Car records each runner's finishing distance as it passes, closing the field one by one, until the Global Champions, the last male and female, are overtaken.
The greatest winner, though, receiving 100% of the proceeds, is Wings for Life, a non-profit with a mission: to find a cure for spinal cord injury.