The Chiefs have rallied from 10-0 down after 20 minutes to beat the defending champion Crusaders 31-10 and pull off the first upset of the Super Rugby Pacific season in the opening match.

Mid-fielder David Havili scored the first try of the season in the 20th minute on Friday night, and the conversion which followed a penalty by Richie Mo'unga gave the home side a 10-0 lead in front of a large crowd.

The Chiefs were able to stay in a mostly scrappy match and had cut the lead to 10-7 at halftime with a try to lock Brodie Retallick.

Second-half tries to captain Sam Cane, center Alex Nankivell and replacement Cortez Ratima put the Chiefs ahead 31-10, while the Crusaders mostly were locked in their own half or contained by the Chiefs' defence.

New rules applied this season to speed up the game produced a faster game, though often at the expense of structure and the Chiefs adapted more quickly than the Crusaders.

The Christchurch-based Crusaders were forced to make a large number of tackles in the second half and missed too many, and were outscored 24-0.

"I thought we hung in there really well in the first half when we put ourselves under a bit of pressure," Chiefs captain Cane said.

"I thought in the second half we got a lot of that right.

"A lot of belief in this team. We feel like we've been building for a couple of years so it's a good start to our season."

The Crusaders were on top early, winning the set piece battle and Havili scored when Cane was in the sin bin for a professional foul.

Retallick scored in the 33rd minute after a break by Shaun Stevenson set up an attacking lineout. Halfback Brad Weber scooted through a gap and Retallick was on hand as he was throughout the match.

The Chiefs grabbed the lead in the 49th minute with Cane's try and made the lead 21-10 when Nankivell dived over in the 60th.

Ratima made an outstanding break from a scrum to score under the posts when the Crusaders were down to 14 men and five-eighth Damian McKenzie made all of his kicks to accentuate the Chiefs' advantage.

Crusaders 10 (David Havili try, Richie Mo'unga con, dg) Chiefs 31 (Sam Cane, Alex Nankivell, Brodie Retallick, Cortez Ratima tries, Damian McKenzie 4 con, 1 pen)

HT: Crusaders 10, Chiefs 7

Referee: Ben O'Keeffe

Assistant Referees: Stu Curran, Jackson Henshaw

Crusaders:

1. Joe Moody 2. Codie Taylor (VC) 3. Fletcher Newell 4. Scott Barrett (C) 5. Mitchell Dunshea 6. Ethan Blackadder 7. Tom Christie 8. Cullen Grace 9. Mitchell Drummond 10. Richie Mo'unga 11. Leicester Fainga'anuku 12. Jack Goodhue 13. Braydon Ennor 14. Sevu Reece 15. David Havili (VC)

Reserves: 16. Brodie McAlister 17. George Bower 18. Tamaiti Williams 19. Zach Gallagher 20. Christian Lio-Willie* 21. Willi Heinz 22. Fergus Burke 23. Macca Springer*

Chiefs:

1. Aidan Ross 2. Samisoni Taukei’aho 3. George Dyer 4. Brodie Retallick 5. Tupou Vaa’i 6. Pita Gus Sowakula 7. Sam Cane (Co-Captain) 8. Luke Jacobson 9. Brad Weber (Co-Captain)10. Damian McKenzie 11. Etene Nanai-Seturo 12. Anton Lienert-Brown 13. Alex Nankivell 14. Solomon Alaimalo 15. Shaun Stevenson 

Reserves:
16. Bradley Slater 17. Ollie Norris 18. John Ryan* 19. Naitoa Ah Kuoi 20. Samipeni Finau 21. Cortez Ratima 22. Josh Ioane 23. Rameka Poihipi