In fact, an injured Colter himself deferred to Siemian with the game on the line in last season's opener against Syracuse.
With Colter's status uncertain, Siemian could be under center at the start of No. 19 Northwestern's home-opening date with the Orange on Saturday night.
Colter is considered day to day after suffering a concussion on the Wildcats' second play Saturday at California. Siemian entered and finished 18 of 29 for 276 yards and touchdown, helping lead Northwestern to a 44-30 victory.
"(Siemian is) poised and ready to go,'' Fitzgerald said. "We have starter 1A and 1B for (the next) couple of years. Although he doesn't go out there on the first play, he still operates as if he's the starter.''
The performance was reminiscent of the 2012 season opener at Syracuse, as Siemian engineered a 10-play, 75-yard final drive that culminated in a 9-yard touchdown pass with 44 seconds remaining to give the Wildcats a 42-41 win.
Colter, who was banged up after going 14 of 21 for 135 yards with two touchdowns and running for another score, told the coaching staff Siemian would give the team a better chance to win on the final drive.
Syracuse coach Scott Shafer was the team's defensive coordinator last season before being promoted when Doug Marrone left to coach the Buffalo Bills, and he was impressed with how Siemian handled the pressure.
"Their quarterback, Trevor Siemian, is a good football player," Shafer said. "He has great touch and really good vision on the field. We will have a great challenge in front of us going against that offense."
That unit, though, may not have starting running back Venric Mark at full strength as he continues to battle a hamstring injury. He carried only 11 times for 29 yards Saturday, but Treyvon Greenfilled in with 16 carries for 129 yards and two touchdowns.
The defense also stepped up, as linebacker Collin Ellis returned two interceptions for scores on his way to being named Big Ten defensive player of the week.
"We were going to face adversity for the first time, so (we wondered) how were we going to handle it,'' Fitzgerald said. "We have to trust our training, trust the things we've worked on. Guys have to pick up the flag and pick up the slack. That's what you saw from our team.''
The Wildcats are riding a 13-game home winning streak against non-conference opponents that began with a 30-10 win over Syracuse in the 2008 season opener. They'll look to win for the third time in four meetings with the Orange, who fell 23-17 to Penn State last week.
Shafer, however, was happy with the performance of quarterback Drew Allen despite the Oklahoma transfer going 16 of 37 for 189 yards and two interceptions.
"I liked his moxie, I liked his energy and I liked his fight,'' Shafer said. "He made a couple of good throws, took some shots.''
Allen, who attempted only 30 passes in limited action over two seasons with the Sooners, knows he can improve.
"I went out there and I was comfortable," Allen said. "Luckily it's Game 1 and we have 11 more to go guaranteed."
Jerome Smith, who rushed 10 times for 34 yards and added another 39 yards receiving last season against Northwestern, had 16 carries for 73 yards and two touchdowns against Penn State.
Though Fitzgerald has watched that film and has the experience of coaching against Syracuse three previous times, he said facing a new coach adds a different wrinkle to this season's matchup.
"I was really impressed with the way they played against Penn State," Fitzgerald said. "New staff, new coordinators, one game of empirical data - it's not enough to hang your hat on of having a good idea of what you're going to see."
Northwestern cornerback Daniel Jones has been ruled out for the season after suffering a knee injury against Cal that will require surgery.