McGrath lost his legs when he stepped on a landmine in Afghanistan and famously told the paramedics tending to him he would compete at the Paralypics one day.

And he did just that on Thursday, winning by a boat length ahead of Austrian and six-time world champion Markus Swoboda. 

"It's pretty special ... for me to claim the top spot I'm pretty stoked," McGrath told Channel Seven.

"I'd run over the race in my head first - I did that and it actually happened (in the race).

"It's a bit of sense of relief. I was very nervous, I think everyone was.

"I guess there's times when it's quiet you have a bit of reflection time and think what could have happened, and just be thankful my life was saved by the guys on the hill.

"This gold is for me and for all the people who supported me."