Securing just one win from the first three rounds has made their clash at AAMI park doubly important for a Brumbies side still searching for combinations and form.
McKellar made four changes to the squad last week and has made another five starting changes this week, with an addition of firepower on the bench.
“We’ve said from the first day of pre-season that we’re [a squad of] 1-40 and not [game-day] 1-23. I don’t think we’re chopping and changing in critical positions here,” McKellar said.
“[Blake] Enever came in for Carter last week and we won 18 of 19 lineouts … I think as long as you’re not making mass changes around your playmakers, we’ll back whoever we put in there.
“From one week to the next always presents a different challenge in getting the balance right in terms of selection. That’s important.
“But we don’t make changes that we don’t trust or believe in. That was the case last week and that will be the case this week.”
Young gun Valetini is back into a new-look back row, with Tom Cusack shifting to No. 8 and David Pocock remaining on openside flanker.
Pete Samu moves to the bench to give the Brumbies some second-half punch, and both coaches are clearly believe the result will be on the line late in the game with the Rebels also raising eyebrows with changes.
Rebels mentor Dave Wessels has added former Brumby Robbie Abel to the starting side at hooker, despite Anaru Rangi’s brilliant start to the year.
Matt Gibbon and Rob Leota will join Abel in the starting pack and Adam Coleman starts his first game of the season after missing round one.
The Rebels have strikeweapons on the bench in Reece Hodge, Rangi, Luke Jones and Richard Hardwick, who will be itching to get on the field.
The Brumbies believe they’ve got the reserves to match them, with Samu joining James Slipper, Josh Mann-Rea and Chance Peni.
Scrumhalf Lonergan will be playing just his second Super Rugby game and his first since making his debut in the last game of the 2017 season.
Former Hurricanes and Rebels second-rower Douglas gets his first opportunity for the Brumbies, while Carter returns after being rotated out of the side because of a cork.
The Brumbies and Rebels will be playing their third game against each other in six weeks after meeting in a trial match in January and Melbourne winning a round-one derby in February.
“We’re fairly familiar with each other, I’m sure they’ll tweak a couple of things and we certainly learnt a couple of things out of round one,” McKellar said.
“It’s going to be a tough clash down there, it will be physical in an Australian conference game. It’s important, it’s really and eight-point game [on the ladder].”
Speight is back after injuring his hip in the first game of the year, but he adds another try-scoring ace to the Brumbies’ back line.
“Just expecting Henry to do his job really well. Defensively be solid and then in attack do what Henry can do. He’s a powerful, damaging ball carrier who will challenge the defensive line,” McKellar said.
“He’s certainly someone who wants to the ball in his hands and we want to get him multiple carries.”
SUPER RUGBY ROUND FOUR
Friday: Melbourne Rebels v ACT Brumbies at AAMI Park, 7.45pm. TV time: Live on Fox Sports.
Brumbies: 1. Scott Sio, 2. Folau Faingaa, 3. Allan Alaalatoa, 4. Rory Arnold, 5. Sam Carter, 6. Rob Valetini, 7. David Pocock, 8. Tom Cusack, 9. Joe Powell, 10. Christian Lealiifano, 11. Andy Muirhead, 12. Tom Wright, 13. Tevita Kuridrani, 14. Henry Speight, 15. Tom Banks. Reserves: 16. Josh Mann-Rea, 17. James Slipper, 18. Les Leuluaialii-Makin, 19. Murray Douglas, 20. Pete Samu, 21. Ryan Lonergan, 22. Wharenui Hawera, 23. Chance Peni.
Rebels: 1. Matt Gibbon, 2. Robbie Abel, 3. Sam Talakai, 4. Adam Coleman, 5. Matt Philip, 6. Rob Leota, 7. Brad Wilkin, 8. Isi Naisarani, 9. Will Genia, 10. Quade Cooper, 11. Marika Koroibete, 12. Billy Meakes, 13. Tom English, 14. Jack Maddocks, 15. Dane Haylett-Petty. Reserves: 16. Anaru Rangi, 17. Tetera Faulkner, 18. Jermaine Ainsley, 19. Luke Jones, 20. Ross Haylett-Petty, 21. Richard Hardwick, 22. Michael Ruru, 23. Reece Hodge.
Chris Dutton is the sports editor at The Canberra Times.