BRISBANE has to be fearless and smart in Saturday's top-of-the-table Gabba sellout against Geelong, says young defender Alex Witherden.

The Lions have won eight successive matches but will get a genuine test of their premiership credentials in the final fortnight against the Cats and Richmond.

A win on Saturday would give Brisbane top spot with one round remaining.

Witherden said the Lions had to be brave against a Cats outfit that conceded just one goal in their win over North Melbourne at the weekend.

"If you play fearful that's when you make mistakes," Witherden said.

"You become timid and your attack on the ball isn't there.

"It's about continuing to play that fearless, ruthless type of footy that has held us in good stead for 20 weeks until this point."

Brisbane has not played either Geelong or Richmond this season, and although Witherden says it's fair to ask whether the Lions are the "real deal", he's more than happy with their form.

In their unbeaten run since the bye, the Lions have beaten Greater Western Sydney (top four at the time), Port Adelaide and Hawthorn on the road, as well as in-form North Melbourne and Western Bulldogs.

Witherden said they were a completely different team from the one that meekly surrendered to Collingwood by 62 points on Easter Thursday in the club's most recent marquee game.

Dayne Zorko, Mitch Robinson and Alex Witherden celebrate last week's win. Picture: AFL Photos

"We just tried to go too quick at times, which can be a mix of different things," he said.

"It can be crowd, it can be nerve-related and we're even playing a little bit different now to how we were earlier in the season.

"For us it's about playing with composure and sticking to our brand of football and if we do that for four quarters … the result will take care of itself.

"You can't be overawed by the situation, you've got to embrace it and we're really excited about testing out where we're at and I think we'll know a little bit more after Saturday."