Ruan Combrinck scored two tries and created another as the Lions held off the Waratahs 27-22 in Johannesburg.
The win keeps the Lions in the hunt for a play-off place, just two years after they were relegated from Super Rugby, while the losing bonus point was enough to send the Waratahs back to the top of the Australian Conference.
It could have been so much more for the Australian side though, who fought back from 27-10 down only to run out of steam in the last 15 minutes.
Two first-half scores from Combrinck had put the home side in complete control, and they would have been much more comfortable but for some late kicking struggles from Elton Jantjies.
But despite scores from Adam Ashley-Cooper and Rob Horne, the visitors fell short, and are now level on points with the Brumbies at the top of the Australian Conference.
Meanwhile the Lions are just two points off the wildcard places, but have played a game more than their rivals.
The Lions started the quicker with Combrinck's opening try which was made by Jantjies. After some good work by their forwards following a lineout, Jantjies delivered a delightful wide pass to put his winger over in the corner, before converting from the touchline.
The response from the visitors didn't take long, with Bernard Foley knocking over a penalty before Stephen Hoiles managed to sneak over despite suspicions of a knock-on in the buildup.
Foley converted to make it 10-7 but the Waratahs were soon reduced to 14 when Horne was sin-binned for a dangerous tackle on Lionel Mapoe.
Jantjies added the resulting penalty, before Combrinck went over for his second. The Lions flyer was involved at the start and end of the move, making the initial linebreak off a set move before popping up again a few phases later to dive over.
With Jantjies' conversion the Lions led 17-10 at the break, and they soon pushed that lead to ten points with another three-pointer early in the second half.
A moment of stupidity from Jacques Potgieter, who put in a shoulder on Warren Whiteley without the ball, saw him sin-binned and the Lions took full advantage. Again Combrinck was heavily involved, breaking through before offloading for Harold Vorster to sprint over on the right.
At 27-10 it looked all over, but the 'Tahs hit back despite being a man down. Just as Jantjies had in the first half, Kurtley Beale bypassed the defence with a floated pass out to Ashley-Cooper. Foley missed the conversion.
The Lions thought they had their bonus-point try a couple of minutes later when Courtnall Skosan pounced on a loose ball in midfield to sprint over, but Jaco Peyper was eagle-eyed and checked with the TMO who confirmed a knock-on had led to the ball going loose.
Just before the hour Beale was again the creator with another sweet pass, putting Horne over in the left-hand corner, and this time Foley converted from out wide to make it a five-point game.
The momentum was with the visitors but the Lions responded and earned a succession of kickable, if difficult penalties, but Jantjies' radar was off and the final quarter was scoreless.
The Lions won't worry about that though, as they continue an impressive Super Rugby campaign. Michael Cheika's team are still on course for the play-offs, but a home knock-out game will require an improved end to the season.