In a game which appeared destined to end in a draw, Christian Lealiifano slotted a penalty goal after the siren to lift the Brumbies to a 23-20 triumph.

Call it an Easter miracle from the Brumbies' Christian or simply luck, but the win could be season-defining.

It means they keep their buffer at the top of the Super Rugby ladder and the Australian conference, having lost just one of their six matches.

But more importantly the unlikely victory shows the Brumbies have matured and can stay composed under pressure to keep their title aspirations on track.

Winning appeared unlikely when the Bulls scored in the last two minutes to level the score at 20-all and then took possession off the kick-off.

But scrumhalf Nic White arrived as the surprise breakdown hero, forcing a contentious penalty at the breakdown while the siren sounded. Lealiifano stepped up to nail a 42-metre shot and secure victory.

It was an exciting end to an otherwise dour contest dominated by kicking, stoppages and penalties, with just three tries scored.

However, the Brumbies now sit five points ahead of the Queensland Reds, but with the 2011 champions having a bye next week the lead is effectively one point.

The good news for the Brumbies is they have been well below their best in the past two weeks, with opposition teams lifting against Jake White's men.

"What I'm really proud about is that this team has shown we can win the tight ones," White said.

"It's such a tough comp, sometimes you have to grind wins out like that. It's a massive learning curve for everyone.

"If you don't play your best and you're still grinding out wins, that's fantastic for the group. I know it wasn't the most attractive game of rugby … but you have to make sure you adapt your game according to who you're playing against."

Just five days after returning to Canberra from a two-week tour of South Africa, the tired Brumbies almost let a victory slip when their seven-point lead evaporated in the last two minutes of the match.

Bulls centre JJ Engelbrecht scored a runaway try and Morne Steyn converted from the sideline to lock the scores at 20-20 with time running out.

When the Bulls regained possession from the restart, the game looked certain to end in a draw.

But Nic White took advantage of an isolated Bulls attacker and stuck his head over the ball to earn a penalty.

Bulls coach Frans Ludeke was adamant a Brumbies player was offside in defence and his side should have won a penalty before losing possession.

"[I thought the Brumbies were] clearly offside, we've looked at it but that's the game," Ludeke said.

"That's life, we don't want to give it [the penalty] energy. They can't take away our effort."

The Brumbies had every chance to use their tough week as an excuse.

They arrived back in Canberra on Monday after 24 hours of travel, had four changes to their starting XV and managed just two training sessions during the week as they recovered from a brutal tour of South Africa.

The Bulls were also tired, with the clash against the Brumbies the last game of a four-week tour of New Zealand and Australia.

But championship-winning teams can snatch victories when everyone thinks the result is decided and the way the Brumbies remained composed in the clutch moment bodes well for their finals aspirations.

Fullback Robbie Coleman scored the Brumbies' only try as they toughed out a victory which could prove vital in their campaign.

"We're a side who knows how to get the points when we need to," skipper Ben Mowen said.

"You want your game to keep evolving … there are certain wins you have to grind out. There are a lot of factors as to why it was a challenging week, but they're never an excuse for a loss. This was a disjointed week, the challenge for any side is to come home and perform … a grinding win is four [competition] points."

The Brumbies' next task is taking on the Southern Kings at Canberra Stadium on Friday night.

ACT BRUMBIES 23 (Robbie Coleman try Christian Lealiifano 6 pens) bt PRETORIA BULLS 20 (JJ Engelbrecht, Jurgen Visser tries Morne Steyn 2 cons 2 pens) at Canberra Stadium. Referee: Jonathan White. Crowd: 13,735.