The Brumbies are the only Australian team through to the Super Rugby finals despite a more competitive showing across the Australian conference this season.
Winning the Australian conference secured them a home quarter-final, to be played next Saturday against the Sharks, who won their final match in the 81st minute on Sunday morning.
McKellar said there was a feeling that the Brumbies had an opportunity to generate some optimism around rugby in the playoffs.
“I do think there's a sense that we're representing the country,” he said.
“You get a bit sick of rugby getting beaten up in Australia for one reason or another so I'd love for us to keep working hard and put some really positive stories together for our own players and group to remember but also for rugby to get some positivity over the next few weeks and I'm confident we can do that.”
Saturday night's win was a club record-equalling sixth victory in a row and seventh in a row at home.
It's a run of wins that propelled the Brumbies into the position they are in after round 18 and handed them some crucial momentum to take into finals.
The Brumbies have kept their team fairly consistent in recent weeks and McKellar said there were no plans to make any drastic changes ahead of next weekend.
“I think we've had confidence and belief for a while now,” he said.
“You see that in moments like we had tonight when we were in under the pump.
“We're not going to go and change a whole lot.
“We're obviously excited, we're really proud of the position we've put ourselves in but we've just got to keep going about the day-to-day process and get our preparation right and turn up here next Saturday night and put in a good performance against a quality team. “
Selection won't be easy for McKellar with players like Tom Wright and Andy Muirhead stepping up in the absence of Toni Pulu and injured Henry Speight, who is expected to be available next week.
"There's going to be a lot of tough choices and some difficult conversations," he said.
'I think that all comes back to that it's a 40-man squad and everyone's going to contribute and play their role."
Reds coach Brad Thorn knows a little about finals rugby having played for the legendary Crusaders outfits and he said Queensland would be getting behind the Brumbies.
“Yeah, big games, finals footy steps up doesn’t it?,” he said.
“The thing that’s great about finals is almost a brand new competition and it’s game on and you take one game, it’s all or nothing and you get past that.
“The Brumbies lads, good lads, good people down here. We wish them well and we’ll see how they go.”