But news of Sio's potential injury-forced break could be offset by the Waikato Chiefs juggling their own concerns and the need to rest some key players as part of a New Zealand rugby agreement to manage player work loads.

The Chiefs are weighing up whether to rest All Blacks Damian McKenzie and Anton Lienert-Brown given there are just two games left in the regular season and the duo need to fulfil a stand-down agreement.

The selection headache is amplified by the absence of the world's best second-rower Brodie Retallick, who is expected to be ruled out for another week with a pectoral problem.

The Brumbies will fly to Auckland on Thursday morning and could be bolstered by the return of Allan Alaalatoa and Lachlan McCaffrey for another sudden-death showdown in the bid to save their season.

Alaalatoa's presence would help cover the loss of Sio, while McCaffrey would add valuable back-row depth to the bench for a clash in Hamilton.

The Brumbies haven't given up hope of forcing their way into the finals for a sixth consecutive year and a riding a wave of momentum after ending their trans-Tasman drought last weekend.

"We have spoken about [finals chances] and after winning last week we've had a look. The thing is we're up against a really strong Chiefs team so we know what to expect," said fullback Tom Banks.

"I think we've got to wait on some results but definitely after winning on the weekend it's awesome to be in contention so hopefully results go our way.

"It was good to break that (New Zealand) hoodoo and it's a good building block for this weekend against the Chiefs."

The Chiefs' selection uncertainty will give the Brumbies a glimmer of hope for a daunting mission to win their first game in New Zealand since 2014 and trying to beat the Chiefs at home for the first time since 2007.

The Chiefs went on an attacking rampage against the Otago Highlanders last weekend, scoring 42 points in the first half to send a message to the rest of the finals contenders.

The Brumbies have found their own form as well and are chasing four consecutive wins to stay in an unlikely battle for a finals berth.

Coach Dan McKellar is expected to stick with combinations, but co-captain Sam Carter is facing at least one more week on the sideline as he continues to struggle with a frustrating back problem.

That opens the door for Blake Enever, who has almost started more games this year than he has in his career.

Two-Test Wallaby Enever played 80 minutes in the impressive win against the Wellington Hurricanes last week and said the players wanted to capitalise on their winning momentum.

"We all know from what people are saying that we've got a mathematical chance of playing in the finals, but that's about as far as we've looked," said Brumbies lock Blake Enever.

"We've been enjoying the footy we've been playing and we can't do anything more than keep working on that. We'll keep pushing and refining as much as we can.

"It's good to see we've been learning and there's a bit of growth of being able to finish games or put teams to the sword.

"I think this year is probably the most starts I've had. I've enjoyed the role I've had in the team ... but the challenge for locks here is tough. I've been loving the game time and getting that balance right."

SUPER RUGBY ROUND 18

Saturday: Waikato Chiefs v ACT Brumbies at Waikato Stadium, Hamilton, 3.15pm. TV time: Live on Fox Sports.