That's why the Queanbeyan junior has vowed to give his all and throw himself into every contest when the Brumbies play against the NSW Waratahs on Saturday night in the biggest Australian derby in 12 years.

Four years ago Coleman was leading the Australian sevens side at the Commonwealth Games in Delhi wondering if he would ever get his chance to achieve his dream of playing for the Brumbies.

Had the Brumbies been knocked out of title contention this season, Coleman would have been in Glasgow chasing a gold medal and he has a dream to go for gold at the Rio Olympics in 2016.

But after an injury-riddled three years, the 23-year-old finally feels settled in Super Rugby, has enlisted Clyde Rathbone as a mentor and his blistering speed and try-scoring form has put him on the cusp of a shock Wallabies call-up.

No one has ever doubted Coleman's speed. But at 179 centimetres and 83 kilograms, it's his diminutive frame which attracts attention in a rugby world infatuated with big, bustling wingers.

"I've never felt like I'm too small or not strong enough. In my first three Super Rugby games [in 2011] I played inside centre against Tana Umaga, Sonny Bill Williams and Ma'a Nonu," Coleman said.

"I love the contact work. My strength isn't my size, it's my speed and acceleration. But I've never felt small. If you worry about it too much, it won't work out and I've never noticed it.

"But [coach Stephen Larkham] said to me at the start of the year that he doesn't care if I'm 95 kilos or 75 kilos, he just wants me to be where I'm at my strong best."

In a match boasting 22 players in the Wallabies squad, a NSW-ACT rivalry and with a grand final berth on the line, it's easy to forget about pint-sized Coleman.

Coleman was dubbed the "Prince of Queanbeyan" by former Brumbies captain Matt Giteau in his breakthrough season in 2011.

Since then the 23-year-old has struggled with injuries, including neck problems, knee troubles, groin strains and the debilitating osteitis pubis.

At times he was so frustrated that he could see his Super Rugby ambitions slipping away while the Brumbies powered on without him.

In previous years Coleman had to stretch for six hours before he played or trained just to make sure his body could cope.

But he finally feels comfortable on the field, scoring eight tries in his 14 games this season to be the Brumbies top scorer.

"The biggest thing is that the last two years I've been plagued by injuries, I wasn't playing games so people didn't understand that I was sore," Coleman said.

"Just to run fast hurt. To get up for games was a six hour stretching session, it was a nightmare. Now I feel better. I still have to put the hours into getting my body right, but I'm getting better. I've got no excuses now."

Coleman is contemplating a break from Super Rugby in 2016 to chase Olympic success with the Australian team in Rio.

The Brumbies are willing to help him on his pursuit of a dream gold medal, as long as it doesn't affect his Super Rugby duties.

Brumbies coach Stephen Larkham said one of the toughest decisions he's made this season was having to leave Coleman out of the game-day squad for the first match of the season.

But since then the speedy winger has launched an undeniable case to be included every week.

"He's in the right frame of mind this year and he's keeping a couple of Wallabies on the bench, his form certainly warrants selection," Larkham said.

"He's different to the big, bustling wingers, but he throws his body in there. He's very competitive and aggressive on the ball. He's super quick and agile, absolutely suited to this team."

Coleman was almost called into the Wallabies camp earlier this year and Test scrumhalf Nic White insists he would be a perfect fit for international rugby.

"You could see in his eyes this pre-season that he was going to take any opportunity he got, he didn't know in what position that would be but he knew he would take it," White said.

"Clyde has a real strong confidence that Robbie can go to the next level. He's skilful, he's quick and he won't let anyone down physically [if he's picked for the Wallabies].

"There are always those doubters out there, but he's as tough as nails and I'm certainly confident when I'm inside or outside him."