Spence will don the green and gold in Dohar, Quatar, in October.

It will mark the first time the 33-year-old has represented Australia.

He told The Courier the selection felt surreal.

"The progression in my running has come as a massive surprise," he said.

"It has never been a dream because it has never seemed realistic until the past couple of years.

"I would've laughed if someone told me three years ago I'd make an international team."

His selection follows impressive performance in the Lake Biwa marathon in Japan.

He was one four Australians to finish under the world championship qualifying time, but he will be the only one to make the journey to Qatar.

"The event will be run in pretty oppressive conditions and not a place where you will enjoy running a marathon, and I was the only one that put my hand up," he said.

"The race is run at midnight, and it's going to be about 30 degrees."

The race will be the toughest ever undertaken by Spence, who admitted he hated running in hot weather.

He said his three-month training regime would include running in heavy clothing and spending time in saunas.

"It's a championship race which is different than anything I've done before when it's mainly just been me verses the clock, he said.

"There is a lot of weight attached with where you finish at the world championships and everyone fights for every placing."

He said he would aim to run a smart race.

"I want to execute my game plan on the day and finish the race strong," he said.

"There will be a lot of people who wont handle the conditions well, so hopefully I see myself move through the field later on late."