The up-tempo Brumbies beat the new-look Rebels 50-19 at Seiffert Oval to start their year with a confidence-boosting win, but the scoreline was overshadowed by the looming selection decisions McKellar will face in the coming weeks.

Tom Cusack got first crack at the vacant No. 7 jersey and his tireless work-rate impressed, but Lolo Fakaosilea and Lachie McCaffrey were equally as good as the trio battle to get their chance in David Pocock's absence.

Joe Powell, Matt Lucas and Ryan Lonergan are chasing scrumhalf game time, and Lucas was one of the stand outs in his first game for the Brumbies after leaving the NSW Waratahs last year.

Playmakers Kyle Godwin and Wharenui Hawera also looked strong, but they have their own tough battle with Christian Lealiifano to be added to the inside backs for a trial against the Waikato Chiefs on February 14.

The selection uncertainty was a good headache for the Brumbies, while the Rebels will now add their Wallabies star power back into the squad after both teams took tentative first steps under new coaches.

McKellar and Rebels counterpart Dave Wessels will face very different challenges this year.

McKellar is replacing Stephen Larkham and has the task of trying to lead the Brumbies into their sixth consecutive finals series and chase a drought-breaking Super Rugby title.

Wessels is trying to blend players from the axed Western Force into the Rebels set up as they set their sights on being genuine contenders this year.

McKellar drew first blood, but both teams left plenty in the tank in terms of star power and set plays, with neither willing to give too much away before they meet again in the third game of the regular season.

"It was a good start. I'm really happy with passages in terms of how we want to play the game," McKellar said.

"I thought there was a good mixture in the second 30 minutes and then we got a bit loose at times. It wasn't perfect and at times we were rusty. But we want to play fast and with good tempo, the challenge now is doing it longer.

"Some individuals stood up and it looks like we got through injury free, so that's a positive. Matty Lucas was good, Isi Naisarani was outstanding and I thought Lolo [Fakaosilea] was strong. Most guys played really well."

Wessels' leadership galvanised the Force in horrid circumstances last year and it's hoped he will bring the same resilience to Melbourne to rebuild the club.

"I think we ticked a lot of boxes in the first 40 minutes in terms of detail, and in the last 40 minutes I think a lot of young guys showed great intensity," Wessels said.

"...It's definitely something to build on. You've got to remember this was the first time a lot of us had played together.

"To get continuity in parts of the game was great to see. But we have some big work-ons ... we slowed down and just played differently in the attacking zone and that will be a real focus [to fix] going into the game."

The Brumbies have tweaked their game plan under McKellar, but they also showed they've got old favourites up their sleeve this year. Hookers Robbie Abel and Connal McInerney scored three tries between them, while forwards Sam Carter and Nasairani also crossed the line.

Henry Speight scored the opener after a Tom Banks intercept, rising fullback Andy Muirhead dived over from close range and ACT junior Len Ikitau put the icing on the cake.

"It was good to get the win and hit the ground running, especially for the new guys. It builds confidence," Speight said.

"The games have come around pretty quick, I was blowing pretty hard and knew I was back into game mode. Still blowing out a few cobwebs after eight seasons ... brushing off the rust."

For the Rebels, winger Kitione Ratu, former Australian sevens player Henry Hutchison and Sione Tuipulotu scored, but the Brumbies led 19-5 at the first break, 31-12 at the second break and 50-19 at the end of the match.