Replacement fly-half Mitchell Hunt has slotted one of the great Super Rugby dropped goals to sink the Highlanders and extend the Crusaders unbeaten season.

Hunt landed a remarkable 45m pot nearly 3min after the fulltime hooter sounded in Christchurch to carry the competition leaders to a 25-22 win. A draw looked on the cards until first five-eighth Hunt, with nothing on, heaved a kick which scraped over the cross bar and prompted all-in celebrations from his teammates.

A 14th win from 14 games ensures the Crusaders will be New Zealand conference champions. It also snaps a winning streak of the Highlanders, which had stood at a franchise-record nine games.

The Crusaders remain on track to become the second side to go through a Super Rugby season unbeaten, matching their own title-winning team of 2002. They have made a habit of snatching late wins, with Saturday's performance similar to when they beat the Highlanders, also by three points, with a late comeback in Dunedin in round two.

Victory over the Hurricanes in their next match, in Wellington in six weeks' time, would also ensure they finish ahead of South Africa's Lions as top qualifiers for the play-offs.

Once again there was no shortage of character from coach Scott Robertson's team, who led 19-10 at halftime. They trailed 22-19 when Highlanders winger Waisake Naholo crossed twice in the space of four minutes after halftime. The second, via an intercept and 75m run, meant All Blacks flyer Naholo has bagged a double in four successive games against the Crusaders.

The hosts slowly re-established control up front, with Hunt's 76th-minute penalty levelling the scores before his last-gasp heroics.

Clinical early execution pushed the Crusaders 12-0 ahead through tries to halfback Mitchell Drummond and winger Seta Tamanivalu.

The Highlanders struck back through a converted try to winger Richard Buckman and a penalty to first five-eighth Marty Banks. Both came while the Crusaders were reduced to 14 men following a yellow card shown to flanker Heiden Bedwell-Curtis for a professional foul. Bedwell-Curtis made amends when he scampered over for his team's third try on the stroke of halftime.

There will be concern in both camps, and from All Blacks coach Steve Hansen, following second-half injures to Ben Smith and Ryan Crotty.

Highlanders fullback and captain Smith, playing his franchise-record 128th game, left the ground for a concussion test and never returned. Crusaders second five-eighth Crotty suffered apparent shoulder damage and was escorted off.