Larkham watches from the sidelines after injuring his arm

ACT suffered a grievous blow just before the half-hour when key playmaker Stephen Larkham was forced off with elbow damage.

While the fly-half was still receiving treatment on the pitch, the Crusaders went in front with a superb try from Marika Vunibaka.

The impressive Mauger was twice involved in the move, captain Reuben Thorne giving the scoring pass for the Fijian wing to sprint away to the right corner.

Mehrtens was unable to convert in the windy conditions, and the Brumbies were grateful for George Gregan's cover tackle to prevent Vunibaka scoring his second try.

But the All Blacks record points-scorer extended the lead to 11-3 with the last kick of the first half, and edged the Crusaders nearer victory with his third penalty 14 minutes into the second period.

The Brumbies came out firing on the resumption but were unable to find a way through an inspired Crusaders defence.

Jack was outstanding in the line-out

Twice, after 46 minutes and just before the hour, they launched sustained attacks on the Canterbury line, but failed to break through.

Walker did reduce the deficit with a penalty 15 minutes from time, but Jack's line-out steal on a Brumbies throw eased the pressure.

Eight minutes from time Justin Marshall's pass to Vunibaka was intercepted by Walker for a try that he converted himself to set the stage for a nerve-wracking finale.

But Canterbury quickly dispelled any throughts of a late ACT comeback as Mehrtens drilled home a 74th-minute drop goal.

Moments later, the Crusaders swept the ball along their backline and Mauger's cut-out pass released Ralph to score in the left corner.

With the crowd at the Jade Stadium already celebrating, Ralph intercepted a pass from Larkham's replacement Julian Huxley and sprinted 80 metres to crown victory.