Chasing their eighth title and first since 2008, the Crusaders will remain in Christchurch next week to meet either the Stormers or the Waikato Chiefs who play later on Saturday in Cape Town.
Driving rain and wind greeted both teams at a sodden Rugby League Park but the conditions played into the hands of the home side's dominant pack while dampening the Highlanders' attacking firepower.
Front-rowers Joe Moody and Codie Taylor rumbled over for tries to drive the Crusaders to a 17-0 lead at halftime that the Highlanders were unable to budge in the second half.
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"It wouldn't have been the prettiest to watch but both sides just got on with it and didn't complain," a shivering Crusaders captain Sam Whitelock said pitchside.
"The weather was great for us and we really embraced it, we knew if we could be clean on the penalty count we would give ourselves a great opportunity."
With severe flooding and three South Island regions under a state of emergency, the Highlanders' preparations were thrown into disarray by the weather, their flight to Christchurch cancelled on Friday and their arrival delayed until seven hours before kickoff.
The 2015 champions hardly laid a finger on the ball in the first half and committed a rash of penalties to give the Crusaders all the momentum.
"I thought technically they were probably a bit smarter in the way they played," Highlanders captain Ben Smith said.
"Once they got down into our 22, they used the ball really wisely."
The Highlanders emerged after the break with renewed commitment and stopped their opponents from scoring but were unable to capitalise on their few drives forward.
Crusaders flyhalf Richie Mo'unga slotted an early penalty but missed another shot 20 minutes later that would have stretched the lead to 6-0.
The Crusaders' forwards then flexed their muscles, however, winning a decisive scrum near the half-hour mark to win a five-metre line-out.
A few minutes of bashing against the Highlanders' defence along the try-line ended with referee Angus Gardner awarding a contentious pick-and-go try to prop Moody under a pile of players.
Controversy threatened again five minutes later, when the Crusaders rumbled over from a line-out drive and were awarded the try on the field.
It was cancelled moments later after the television match official was unable to see the ball grounded.
It scarcely mattered, as the Crusaders rumbled forward again, allowing hooker Taylor to score another pick-and-go try on the stroke of halftime.
Mo'unga duly converted and the Crusaders maintained their iron-willed discipline to close out a rousing win and warm the hearts of rain-soaked fans in the terraces.
(Reporting by Ian Ransom in Melbourne; Editing by Amlan Chakraborty)
