Brett Robinson has personally called his mate Andy Buchanan to tell the marathoner he'd be replacing him in Paris.

Australia's fastest person over 42.2km withdrew from the Olympics on Friday because of a glute injury.

Buchanan, 33, now has two weeks to prepare for his Olympic debut alongside Pat Tiernan and Liam Adams on August 10.

"When I saw Brett was calling, I let it ring a few times as I was worried it was a pocket dial," he said.

"To get the news from Brett himself shows the type of person he is.

"We are mates, but it was still an awkward situation. I was disappointed for him that he couldn't compete but at the same time stoked that I get an opportunity.

Robinson broke Rob de Castella's 36-year-old record at the Fukuoka International Marathon two years ago, clocking two hours, seven minutes and 31 seconds to slash 20 seconds off the mark.

"Brett has changed the Aussie men's marathon. He was the first to have the confidence to push the boundaries. Pat, Liam and I are just following in his footsteps," Buchanan said.

⁠"I don't think it has sunk in just yet.

"You normally spend months preparing for a marathon and it's quite a strange feeling only having two weeks' notice but I'm excited for the opportunity and the challenge"