Discipline under intense Brumbies' pressure proved the difference for the Blues with their competition-topping 21-19 last-minute win in Super Rugby Pacific in Canberra on Saturday.

As a top of the table contest, the Blues were determined to finish first, and they achieved that with a round to play, their final game being in Sydney against the Waratahs.

Coach Leon MacDonald said, "The penalty count was huge and I thought our discipline was fantastic which probably proved the difference." 

Making a firm statement was also important, because there was every chance the Brumbies would still be in the contest in its final stages, and they wanted to put in a good showing against them.

"There was a lot to be proud of. It wasn't a perfect performance in terms of execution but, I think in terms of effort and hunger, and a little bit of heart there's a 10 out of 10 for me in a lot of those areas," he said.

MacDonald described it as a 'massively gutsy' win.

"The Brumbies were huge in their intensity, and I thought they lifted up a gear from their performance against the Crusaders, and brought in some real heat at the breakdown and in their defence."

That was enough to prevent the Blues from getting a scoreboard break.

"We were bashing away at the line, applying a lot of pressure, and they were able to hang in there and make that strike late in the game that nearly gave them the win," he said.

They had known they were heading into an arm wrestle. That was always the case in Canberra and made the win more pleasing, he said.

Once going behind with 90 seconds left, the leadership group reflected their maturity in the messages they gave the players for their final assault resulting in first five-eighths Beauden Barrett's dropped goal.

"They were clear in what they wanted to do and were able to defend well, get the ball back and execute at the end of the final play which is just massive," he said.

Resetting scrums and continual stoppages meant little advantage was applied, and the hot contest at the breakdown had provided plenty for the referee to think about.

"There was a lot going on there from both sides," MacDonald said.

The Blues trained with a desire to show good pictures to the referee when they could to reduce the decision-making as much as possible.

MacDonald was impressed with the way Anton Segner performed on the blindside flank after the side lost three players in that position during the week. He had been busy, and in stepping up he showed he had a big future.

Lock Luke Romano and prop Karl Tu'inukuafe had performed well off the bench, while prop Nepo Laulala added some punch in the forwards with his physicality.