The Brumbies ended the Highlanders unbeaten run and went to the top of the Australian conference with a 33-26 Super Rugby victory in Canberra.
The only remaining unbeaten team left in the tournament are the Stormers who play the Lions later today. The result may have cost the Highlanders dearly though as they lost playmaker Colin Slade in the 52nd minute with a severe ankle injury and his season may be over.
The immediate medical report from the Highlanders medics was that Slade had a "serious fracture in his left ankle" and was taken straight to Canberra Hospital where an operation seems likely.
Slade, who injured his groin as Dan Carter's replacement for the All Blacks in last year's World Cup, has had dreadful luck with injuries, breaking his jaw twice in recent seasons and only playing seven games in two years.
The Highlanders have already lost Lima Sopoaga so losing Slade as well will severely test their depth.
The two-time Super Rugby champion Brumbies won their third match under new South African coach Jake White three tries to two with fly-half Christian Lealiifano landing three conversions and four penalties.
The Brumbies remained unbeaten in three matches at home this campaign with their only loss coming last weekend 29-22 to the Chiefs in New Zealand.
The Highlanders continued to find Canberra a difficult place to win and have now won only twice in nine visits.
"We back ourselves, you can see from the way we play that there's huge trust in each other," Brumbies skipper Ben Mowen said.
"The only way we've done that is by working hard and we trust that the work will pay off."
Winger Joseph Tomane scored two tries in the opening 16 minutes as the Brumbies raced to a 17-3 lead.
The Highlanders however managed to pull back and trail 17-13 when All Black Hosea Gear sliced through to put Aaron Smith over, but the Brumbies led 20-13 at halftime.
The resolute Highlanders kept within touching distance with their hosts and levelled the scores twice in the second half.
The clinching try for the Brumbies came in the 63rd minute when outstanding young open-side flanker Michael Hooper picked up a loose ball from a maul and charged over for Lealiifano to convert for a 33-26 advantage which they safely held to full-time.
"It was a pretty disappointing for us but I take my hat off to the Brumbies, their intensity and physicality at the breakdown was top-notch and they disrupted a lot of our ball," Highlanders skipper Jamie Mackintosh said.
"The disappointing thing for us is that we worked our way back into the game and were in a position to win it but just lacked a bit of patience in attack and at the end of the day we just couldn't finish it."
The Brumbies are at home again next weekend against South Africa's Sharks, while the Highlanders host the Melbourne Rebels in Invercargill next Friday.
Final Score Brumbies 33 (20) Highlanders 26 (13)
Tries - J. Tomane 2, M Hooper
Pen - C. Lealiifano 4
Con - C. Lealiifano 5
Tries - A Smith, S Treeby
Pen - C Slade 2, C Noakes
Con - C Slade 2
Drop - C Slade
Referee: Louren van der Merwe
Assistant Referee 1: Marius Jonker
Assistant Referee 2: Simon Moore
TMO: Steve Leszczynski
1. Ben Alexander ,2. Stephen Moore ,3. Dan Palmer ,4. Leon Power ,5. Sam Carter ,6. Peter Kimlin ,7. Michael Hooper ,8. Ben Mowen (c) ,9. Nic White ,10. Christian Lealiifano ,11. Henry Speight ,12. Pat McCabe ,13. Andrew Smith ,14. Joe Tomane ,15. Jesse Mogg
Replacements:16. Anthony Hegarty ,17. Ruaidhri Murphy ,18. Scott Fardy ,19. Ita Vaea ,20. Ian Prior ,21. Zack Holmes ,22. Tevita Kuridrani
1 Jamie Mackintosh (C) 2 Andrew Hore 3 Chris King 4 Josh Bekhuis 5 Culum Retallick 6 James Haskell 7 Doug Tietjens 8 Nasi Manu 9 Aaron Smith 10 Colin Slade 11 Hosea Gear 12 Shaun Treeby 13 Tamati Ellison 14 Kade Poki 15 Ben Smith
Replacements : 16 Jason Rutledge 17 Bronson Murray 18 Nick Crosswell 19 Elliot Dixon 20 Jimmy Cowan 21 Chris Noakes 22 Buxton Popoali'i