Western Force scored four tries in a 29-19 victory over the Lions to see them overtake the Brumbies and move into the play-off positions.
Force captain Matt Hodgson scored twice and there were also tries from full-back Jayden Hayward and Chris Tuatara-Morrison as the Perth-based franchise moved up to fourth in the Super Rugby ladder.
A trio of penalties from Marnitz Boshoff had seen the Lions take the lead in the first half, but their lack of creativity in attack, as well as a Corne Fourie yellow card, proved costly.
Both sides struggled to negotiate the increasingly difficult conditions in the second period, with Boshoff claiming a fourth penalty before Tuatara-Morrison appeared to have taken the game away with a third Force try.
Replacement fly-half Elton Jantjies hit back for the Lions but their challenge was stunted when Hodgson raced home a bonus-point score for the hosts.
With heavy downpours at the nib Stadium the game struggled to gather momentum as Boshoff and Sias Ebersohn exchanged penalties.
Force struck first via the boot of Ebersohn before Boshoff, whose efforts in a demoralising Lions campaign were rewarded this week by a call-up to South Africa's training squad, kicked three penalties without reply.
However, when Force hooker Nathan Charles took a blow to the head the Lions were reduced to 14 men as prop Fourie was sent to the sin bin following a recommendation from TMO Peter Marshall.
Force - sporting bright pink socks in support of the McGrath Foundation - made their personnel advantage pay as talismanic flanker Hodgson slipped down the side of the pack to score the game's opening try.
Ebersohn made no mistakes with the conversion and almost claimed a try of his own the very next minute, but Marshall ruled he was held up after he took over from a piercing Nick Cummins charge.
The inevitable second Force try eventually came on the cusp of half time as the hosts worked the ball wide to Hayward, who slipped over the whitewash as they took a 15-9 lead into the break.
Michael Foley's side continued where they left off after the break, working their way through 10 phases as the threatened to break the Lions defence for a third time.
Ebersohn kicked into touch with a penalty and the Force won the line-out before winger Nick Cummins raced over, only for the TMO to rule that there has been an infringement in the build-up.
Force continued to send waves of attack in the Lions' direction and they finally reaped their reward when Tuatara-Morrison crashed through two tackles to dot down.
A poor clearance from Cummins allowed Jantjies to race home the only Lions try of the night and Boshoff's conversion set up a thrilling finale.
Force avoided what would have been an embarrassing slip as Hodgson stretched out to touch down the all-important bonus-point try for the Perth side.
A fourth successive defeat means the Lions' four-match tour of Australasia ends fruitless, while the Force now shift themselves into second place in the Australian conference.