Fullback Joe Roff booted a penalty goal after the fulltime siren to clinch a 23-20 victory for the ACT Brumbies in their Super 12 clash with the Sharks at Canberra Stadium.

The match looked headed for a 20-all draw after the Sharks' five eighth Butch James slotted a penalty goal with just two minutes left.

But the Brumbies refused to settle for a stalemate.

With just seconds remaining, Clyde Rathbone launched the Brumbies' final raid, but when the movement broke down, a blast on referee Steve Walsh's whistle gave them one last chance.

He had awarded a penalty for offside from 30 metres out and right in front. Roff made no mistake.

The Sharks had looked set for a shock victory with just 20 minutes left in the game, as they controlled play and the scoreboard, with a 14-3 lead.

The Brumbies all out commitment to attack, which proved costly in a rain-soaked first half, was their saviour in the second as they passed up penalty attempts.

Twice in the second half the Brumbies declined easy penalty shot, and were rewarded with tries to Mark Gerrard and Bill Young that set up a dramatic climax.

Brought to you by AAP © 2024 AAP