Crowley made only two changes from the team which beat the United States 27-7 last month, sticking with the same starting lineup which lost 38-14 in a warmup match against the Australian Barbarians two weeks ago.
Crowley said his team has built continuity and has enough physical prowess to match the Tongan style of play.
"We've hopefully given them enough game time together so they'll be right," Crowley said Monday. "We look at who we're playing against and what team we think is best to face Tonga, and we consider this is the best possible team to do that and that's where the selections have come from."
Smith came off the bench in both of Canada's recent wins over the U.S. Eagles. Canada won the first match of that series 28-22.
He joins Fairhurst, lock Jamie Cudmore and fullback James Pritchard as the only survivors of the Canada team which beat Tonga 24-7 in a pool match at the 2003 World Cup.
While Tonga opened its World Cup campaign with a 41-10 loss to New Zealand, Wednesday's game will be Canada's first in pool A, which also includes France and Japan.
Tonga has more than just physical might to threaten Canada with.
"The set play is crucial, you've got to get good platform ball so that will be a massive challenge for the guys around the scrum and the lineout," Crowley said. "Obviously the contact area, Tonga bring a real physical game to the table and we've got to match that."
Tonga's solid second-half performance against the All Blacks showed how strong they will be for Canada to break down.
"Defensively they were very good," Crowley said. "They had a couple of glitches, which the All Blacks were able to get through, but their direct pick-and-go game was good, and the scrum is one of the strongest."
Withstanding Tonga's impact in the tackle and speed out wide will be crucial to Canada's chances — which is where defence coach Clive Griffiths comes in.
"You are only as strong as your weakest link," Griffiths said. "These are cliches that we use, but it's true. If you have pride in defence collectively and individually, all these little things make the difference."
Griffiths became involved with the Canadian team when the club he coaches in northern Wales, RGC 1404, struck a deal with Rugby Canada which has involved nearly 20 Canadians playing for the club over the past two seasons.
Seven of those are in Canada's World Cup squad, including five who will start against Tonga — flanker Chauncey O'Toole, lock Jebb Sinclair, props Hubert Buydens and Jason Marshall, and winger Ciaran Hearn
Griffiths was Wales' defence coach when it won the Six Nations Grand Slam six years ago, and he is fast making an impression with his new team.
Canada twice beat the Eagles with less than 40 per cent possession. In the second of those warmups, Canada was down to 13 players at one stage, after two sinbins, but the defence held out.
"Because of that ice hockey mentality, they (Canadians) kind of want to get in there and have a go," Griffiths said.
Hooker Pat Riordan will captain the team and wins his 40th cap for Canada, as does Pritchard.
"There's nothing to say you can't beat a team that's five or six or 10 places above you, so in that sense we are chomping at the bit to show what we can do," Riordan said. "Of course we think we've got a chance to win."
He will be joined in the front row by Hubert Buydens and Jason Marshall, while Jebb Sinclair partners Cudmore at lock.
Left-winger Phil Mackenzie will be looking for his fourth try in as many games, although one was uncapped against the Barbarians.
Crowley has some youthful backs in his reserves — with 21-year-old centre Conor Trainor, 23-year-old scrum half Sean White and fly half Nathan Hirayama offering the possibility of fresh legs late on Wednesday in Whangarei.
Canada: James Pritchard, Ciaran Hearn, DTH Van Der Merwe, Ryan Smith, Phil Mackenzie, Ander Monro, Ed Fairhurst; Hubert Buydens, Pat Riordan, Jason Marshall, Jebb Sinclair, Jamie Cudmore, Adam Kleeberger, Chauncey O'Toole, Aaron Carpenter. Reserves: Ryan Hamilton, Scott Franklin, Tyler Hotson, Nanyak Dala, Conor Trainor, Sean White, Nathan Hirayama.