Seta Tamanivalu's sweeping try with less than two minutes remaining has sealed the Crusaders a thrilling 30-27 come-from-behind Super Rugby win in Dunedin.

A thrilling South Island derby was decided in the last half-hour as the visitors' forwards got on top and laid the platform for all four of their tries.

Trailing 27-6 soon after halftime, the Crusaders stormed back to post their second narrow win following last week's 17-13 home defeat of the Brumbies.

It was more pain for the injury-hit Highlanders, who were pipped last week by the Chiefs and have now lost successive games at home for the first time in four seasons.

They lost All Blacks fullback and captain Ben Smith last week to concussion and look like they could be without flanker James Lentjes (shoulder) and hooker Adrian Smith (knee) for a spell after both were early casualties.

Match officials will also review a pivotal incident with seven minutes remaining when Highlanders centre Malakai Fekitoa didn't contest a high ball, resulting in a heavy fall for Crusaders fullback David Havili.

All Blacks No.13 Fekitoa was shown a yellow card and, in his absence, the rampant Crusaders created overlaps to cross twice.

Whetu Douglas put the visitors within sight before three-Test back Tamanivalu capped an irrepressible attack from deep, eventually stepping out of tackles from Lima Sopoaga and Tevita Li to cross in the corner.

It silenced a crowd which had expected the Highlanders to roar away when All Blacks winger Waisake Naholo bagged his second try, a brilliant score which began when Sopoaga's chip over the backline was fielded by Fekitoa.

Tries to flanker Gareth Evans and Naholo helped the hosts grab a flattering 17-6 halftime lead after the Crusaders had dominated the opening quarter.

A turning point came when a dominant Crusaders scrum earned them a penalty try.

Havili scored from a slick blindside move soon before suffering the fall which forced him from the field.