The change comes two days after the Gators dropped their second game of the season to Tennessee 24-10 in an erratic offensive display. Zook remained adamant that former starter Ingle Martin will be prepared to play if necessary.
"Not going into the game, it's not a rotation," Zook said. "But if Chris struggles and has some problems, Ingle knows that he's going to be going out. I mean, I'm not afraid to stick Ingle in there. I just want to see what Chris can do."
Leak was put off-limits to the media Monday, and Florida's sports information department said Martin ended his workout 45 minutes early because of class obligations.
"Chris is ready," said Curtis Leak, who hadn't yet heard from his son. "This is part of everything he envisioned when he committed to Florida. If he fails, it will be the first time he's failed at anything in his life."
Leak told his father Sunday coaches held a team meeting to discuss the situation. On his teleconference earlier in the day, Zook said he would not make a decision until he had talked to his players.
Through an anemic passing performance, Martin finished 16-for-32 against the Volunteers with one interception and 205 yards.
Leak, who played far less, was more impressive in the few passing opportunities he had. He completed 9-of-12 for 76 yards and one interception. Both Martin and Leak were sacked once.
In his first series of the game, Leak's inexperience showed as he fumbled one snap and bobbled another. But Zook was quick to defend the true freshman.
"Ingle dropped a snap also," Zook said. It was an electric atmosphere. I even made a comment to note during the game that we need to get him out of the shotgun, but he likes being in the shotgun. He just sometimes takes his eye off the ball."
After a 2-2 start, Zook fell under heavy criticism following the game. He said Sunday his coaching staff would enter a self-evaluation period in light of the uninspiring offense.
But he continues to stand by his coaching to this point.
"Ingle is playing fine," Zook said. "And if I had it to do over again - what we've done - I would do exactly what I've done. I just think this is something that I want to look at after looking at the game."
Leak, from Charlotte, N.C., threw a national high school record 185 touchdown passes during his career at Independence High. He joins an elite group of true freshman quarterbacks on the Division I-A level.
"We want the other teams to be skeptical," Curtis Leak said. "I don't want them to know how great a player he is. I think Ron has done the right thing."