Smiler is playing to win a new contract in Canberra, vowing to make the most of his opportunities on the field even if that means taking down the biggest professional sportsmen in Australia.

At 193 centimetres and 111 kilograms, Smiler is set to be the smallest starting lock in Super Rugby this weekend as he keeps his place to play against the Waratahs on Friday night in a duel with 140-kilogram Skelton.

Smiler is unfazed by their distinct size difference, adamant he's up for the challenge as the Brumbies attempt to stretch their lead in the Australian conference.

"He's a big boy, a heavy lad. I guess I'll just have to push even harder and that's it," Smiler grinned. "You've got to take away his room to run, as soon as he builds up a bit of steam he will run over you.

"You've got to chop him low, can't take him high and take away that room to run, that's why line-speed is a major focus for us to cut down time and space."

Smiler was forced to bide his time on the Brumbies bench in the first 10 weeks of the season, despite showing some career-best form.

Sam Carter's absence last week opened the door for Smiler to be injected in the starting team and he wants to cement a spot as he enters contract negotiations.

The 29-year-old former Australian and New Zealand sevens player has earned a reputation as a hard worker and a hard hitter in the Brumbies line-up.

He hopes those are the qualities that convince the Brumbies to offer him a new deal beyond the end of the Super Rugby season.

"I like to think [I can add some mongrel], I've worked on being more aggressive and physical over the last three years," Smiler said.

"When you're a big guy, you don't get through as much work. Our game is built on hard work and that's what I hope to bring to the game.

"I'm used to coming off the bench ... I've found myself in the right mental space every week. If you don't perform you'll get pulled back to the bench.

"But that's not my focus, it's just consistency. We've been chatting [about contracts], it is motivation to play. You want to stay here so you want to play well to give the coaches confidence.

"It does play on your mind a little, I'm a family man and it's about security for your family. It's a massive motivation of mine, to play well for your family."

The Brumbies will give Smiler another chance in the second row this week, putting him directly opposite Skelton in the forward pack.

The Brumbies are backing Smiler's hunger for success to combat Skelton's size.

Blake Enever moves to the bench with Carter back in the team, while Rory Arnold will continue his comeback from a back problem in Canberra's first-grade competition.

SUPER RUGBY ROUND 12

Friday: ACT Brumbies v NSW Waratahs at Canberra Stadium, 7.40pm. TV time: Live on Fox Sports 2. Tickets available from Ticketek.