Gregson, 18, will miss the prestigious Zatopek meet in Melbourne next month where he was to contest the Robert de Castella junior 3km race.

The national junior 1500m and 5000m champion had been looking forward to competing.

But tests revealed he had a stress fracture in his fibula after competing at the Noosa 5km Bolt on November 1, when he finished sixth.

"Since about July I've done four or so road races which have been more than 5km.

"I'm usually racing on the grass or the tartan, which is a bit softer than the road, and just the pounding of the race has built up and got me in the end," Gregson said yesterday.

"As a distance runner you always have pains, you're never that far away from an actual injury because you're working so hard.

"If you stop at every pain then you'll never get any training done. I kind of felt it there but I kept doing it for another few days," he added.

"The Noosa was on the Saturday, then on the Monday I thought, 'This is more serious than a little pain.' A week later I had a bone scan and it turned up I had a stress fracture."

This is Gregson's first major injury and while it will keep him out of competition until next February, he will be working in the pool and on a bike as part of his recovery.

"Now I've got this (injury) I'll be a couple of months out but I should be able to get back to where I was and hopefully improve and run well," Gregson said optimistically.

"My main goal is the World Cross Country in Jordan (next March) and I'll still be in the juniors there.

"I'm hoping to start racing at my best again in February."