The Brumbies must play a waiting game with a bye leaving the NSW Waratahs in tenuous control of the Australian Super Rugby conference.
The Brumbies remain leaders of the local brigade after besting the Lions 30-20 in Johannesburg.
The win came at a cost with Wallabies back Matt Toomua re-injuring his ankle and forced off the field after only 25 minutes.
Two points clear of NSW, they return home to Canberra for a bye week, effectively handing their immediate fate over to the Waratahs, who hosts the Crusaders on Saturday at ANZ Stadium in a sequel to their pulsating 2014 final.
The Waratahs kept their title defence on track with a hard-fought 33-18 win over the Sharks in Sydney.
But the Melbourne Rebels blew their chances of making an impact on the Australian front-runners with a 46-29 loss to the lowly Queensland Reds, who pulled off a major form reversal their first game under newly-appointed coaching consultant John Connolly.
The Brumbies will leave South Africa in good shape after their narrow loss to the Stormers was followed by a bonus-point win over the Lions.
Toomua appeared to suffer a recurrence of the problem that required surgery and kept him out of action for over a month.
However a team spokesman said they were hopeful he’d be right for their home clash with the Bulls following the bye.
Skipper Stephen Moore said while the ladder was tight, the week off would help with their recovery to make a charge to the finals.
“We need a week off because we’ve had two really tough games,” Moore said. “We needed that win to keep in the hunt so I’m very proud of the boys.”
As well as hosting the Crusaders in a replay of last year’s gripping final, the Waratahs’ road to glory looks bumpy.
They face the improved and unpredictable Lions in Johannesburg followed by the Cheetahs in Bloemfontein and then a derby against the Reds at Allianz Stadium.
NSW coach Michael Cheika said the ninth-placed Crusaders were a team on the rise, proven in their recent 41-point thrashing of Queensland last round.
He thought the Crusaders, who had the bye this round, would arrive in Sydney full of self-belief.
“When they’re on, they’ve demolished a couple of teams big time,” Cheika said.
“I genuinely think they fancy themselves to come here and beat us.
“It’s going to be a big challenge for us, a big physical battle.”
Mathematically, the Rebels remain a chance but they play two games in South Africa, where they are yet to win a match in eight attempts, as well as the Bulls and Western Force, and need all four wins to have any hope.
The Hurricanes continued their stunning surge at the top of the table with a 22-18 win over the second-placed Chiefs.
Now 13 points clear of their nearest rivals, the win all but wrapped up a Super Rugby home play-off.
The Bulls climbed over the Stormers to lead the South African conference by a point after picking up a losing bonus point in their surprise loss to the Blues.