Harris, 28, makes his CFL starting debut Friday night when the Toronto Argonauts host the expansion Ottawa Redblacks. He replaces veteran Ricky Ray, who suffered a concussion in Sunday's 17-14 loss to the Montreal Alouettes.
The Argos (7-10) must beat Ottawa (2-15) to remain in playoff contention. They also require Montreal to defeat the Hamilton Tiger-Cats on Saturday to clinch second in the East Division and host either Saskatchewan or B.C. in the conference semifinal Nov. 16.
"Absolutely," Harris said confidently when told Friday's contest was a must-win for Toronto. "That's the best kind."
Hamilton would clinch second with a Toronto loss or by beating Montreal on Saturday. The Ticats would finish first — and secure home-field advantage for the East final Nov. 23 — by beating the Alouettes by eight points or more.
At first glance, giving a young quarterback the chance to make his first start against an expansion franchise would seem a perfect scenario for the Argos. But they're the only CFL team not to beat Ottawa this season as the Redblacks defeated Toronto 18-17 in their home opener July 18 the only other time the two clubs met.
"They beat us so they've got our attention regardless," Toronto head coach Scott Milanovich said. "If we don't play well they can beat us, they've already proven that."
The six-foot-three, 209-pound Harris has played sparingly over his three seasons with Toronto, completing 33-of-58 passes for 424 yards and a TD. He was the Argos' No. 3 quarterback his first two years before being promoted to Ray's backup this off-season after Zach Collaros left to sign with Hamilton.
Milanovich said he and offensive co-ordinator Marcus Brady struggled with the decision to start either Collaros or Harris last year when injuries forced Ray to miss seven starts. Ultimately, they went with Collaros, who went 5-2 during Ray's absence.
"Marcus and I went back and broke down every drive relative to points scored and Zach was a bit better," Milanovich said. "But it was very close and almost borderline unfair for Trevor that he didn't get that opportunity.
"He certainly has earned it. His teammates believe in him and I expect he'll play well."
Harris was productive at Edinboro (2006-'09), amassing 11,899 passing yards and 100 TD passes. In his final collegiate game, Harris completed 50-of-70 passes for a Division II playoff-record 630 yards and five TDs while running for two more in a wild 84-63 playoff loss to West Liberty.
Unfortunately for Harris, he only had one full practice this week as Toronto plays twice within a five-day span.
"It just felt natural to be in there, to take the reps and call the plays," he said. "That can go a long way come gametime.
"I started a lot of games in college, I've played a lot of games and there's nerves every time you step on the field. But once that first snap is over, you usually get those nerves out and just start playing loose."
Ottawa quarterback Henry Burris, a 16-year CFL veteran, said overcoming nerves is challenging for a young quarterback.
"You better get used to loving butterflies because you're going to be feeling them and seeing them fly around you for a couple of days leading up to the game," he said. "The anxiety is going to be flowing the night before when you're trying to go to sleep and constantly start to rehearse plays in your head.
"The most important thing is his teammates are going to rally around him and give him the best chance of knowing that he doesn't need to do everything himself. I think that's the No. 1 thing you have to communicate to a young quarterback because once you press and try to do too much that's when bad things happen."
Milanovich, himself a former quarterback, agrees.
"I don't want (Harris) trying to be a hero from the pocket," he said. "I want him to get through his progressions and if it's time for him to make a play he needs to make it.
"We don't believe our season is over. I told our guys this is our last chance to keep the dream we all have alive, which is to be champions at the end of the year. I think we'll come out of the game playing hard."
Toronto will be making more lineup changes than at quarterback. Rookie cornerback Isaiah Green, who joined the Argos roughly three weeks ago, replaces Vince Agnew (Achilles) while veteran receiver Jason Barnes comes off the six-game injured list to start at slotback.
Running back Curtis Steele (concussion) and defensive lineman Marcus Thomas (foot) also won't play.
Burris will start for Ottawa but head coach Rick Campbell will give backup Dan O'Brien plenty of playing time against Toronto.
"I want to get him in there where he gets into the flow of a game and is directing an offence and hopefully that's for a big chunk of time (Friday)," Campbell said. "I think it only helps us to know in the off-season what our depth is at quarterback.
"He's done some real good things for us but we need to see him play for a good chunk of the game and see how that goes."
Burris said he's fine with that.
"I know I'm starting things out, we'll see what happens from there," he said. "Regardless of what they're asking me to do I'm going to make sure I am ready.
"I'm making sure (O'Brien) is prepared and able to compete against whatever Toronto throws at him. They're going to bring the heat. They bring a lot of different blitz packages and love getting pressure."
Ottawa can certainly spoil Toronto's playoff plans, a role Campbell kind of relishes.
"That's always an added bonus, that we get to have an affect on what's going to happen in the playoffs," he said. "We know it's a big game for them but it's a big game for us because we're a team that needs to get better each week."