With star quarterback Braxton Miller on the way to the hospital for evaluation, Guiton took his place and led the Buckeyes to a tying touchdown and two-point conversion with 3 seconds left to force overtime against Purdue.
Guiton wasn't done. He then guided Ohio State into position for Carlos Hyde's 1-yard touchdown run that ended up as the difference in a heart-stopping 29-22 win over the Boilermakers on Saturday.
"I'm still trying to figure that bad boy out," a stunned coach Urban Meyer said after his Buckeyes (8-0, 4-0 Big Ten) remained perfect on the season with the improbable victory. "We won, right?"
Many in a crowd of 105,290 thought the Buckeyes had little or no chance of winning after Miller lay on the turf for several minutes after being thrown down on the next-to-last play of the third quarter. The mood had sunk even lower when Guiton, who had just thrown an interception on his last play, came out with just 47 seconds left, Ohio State trailing 22-14, and 61 yards remaining to get to the end zone.
"The people around me calmed me down and got me ready to go out there and have fun," the senior said.
He did more than have fun.
"Some of the efforts I saw tonight were legendary," Meyer said. "I mean, that was a moment that I'll certainly never forget -- the quarterback jogging into the game, the old right-hander. (He) just did a heck of a job."
After Guiton threw the interception toLandon Feichter with 2:40 left that could have ended Ohio State's hopes, Meyer grabbed Guiton.
"I said, 'You're going to win us a game,'" Meyer said. "He looked right at me. I think he was down but I think that moment kind of picked him up."
Meyer, in his first year at Ohio State, had taken an almost instant dislike to Guiton because of his attitude and lackadaisical work habits, and nearly ran him off the team.
"He was ready to get a one-way bus ticket back to Texas when I first got here," Meyer said earlier this week. "Then he changed really dramatically."
Guiton appreciated the faith his coach had in him, even after the turnover. When he ran onto the field for the final drive of regulation, he passed that confidence on to his teammates.
"(Coach Meyer) told me I was going to be OK," Guiton said. "I told the offense, 'We need to make plays and we're going to get it. So let's go, let's keep our heads up and let's start winning this game.'"
On first down, Guiton threw a long pass to a wide-open Devin Smith for a 39-yard gain.
Battling the clock, the Buckeyes eventually faced a first and goal at the Purdue 2 with 8 seconds left. Guiton rolled to his left and fired a low pass to another seldom used player, Chris Fields. The play was reviewed but was allowed to stand.
Now down by two points, the Buckeyes set up for the conversion. Guiton lofted a soft toss over a linebacker to freshman tight end Jeff Heuerman to tie it.
After smothering the Boilermakers on the ensuing kickoff, the overtime was decided early.
"I wanted the world for the team," Guiton said.
Ohio State got the ball first in the overtime and Hyde scored on a short plunge for Ohio State (8-0, 4-0). When it was Purdue's turn, Caleb TerBush, who had two TD passes, misfired on four passes.
"Before the game we talked about playing 60 minutes. Unfortunately, we played 59 minutes and 30 seconds," Feichter said.
An almost unfathomable win was complete.
Purdue had earlier scored on TerBush TD passes of 83 yards to Akeem Shavers -- on the first offensive play of the game -- and 31 yards to Gary Bush in the third quarter, along with Akeem Hunt's 100-yard kickoff return. The Boilermakers also picked up a safety when Ohio State was called for an illegal block in the end zone in the fourth quarter.
Miller completed 9-of-20 passes for 113 yards with an interception and ran for 47 yards on 12 carries before leaving the game on the next-to-last play of the third quarter.
He ran the ball on first down from how own 24, stiff-armed a defender and sped around right end for 37 yards before being caught by cornerback Josh Johnson, who threw him hard to the turf on his left shoulder.
Miller didn't get up for several minutes -- he was in obvious pain -- while he was attended by several doctors and trainers. Eventually he sat up, then stood on shaky legs for a moment before he was led to the sidelines. He was later taken to the locker room by cart and then on to Ohio State's medical center for evaluation.
Team spokesman Jerry Emig said doctors had run tests on Miller's head, neck, shoulders and knees and there were no symptoms of a concussion or other obvious injury.
Through Emig, Meyer said, "He's doing fine."
The teams had traded touchdowns in the third quarter, with Ohio State taking a 14-13 lead on Hyde's 2-yard run, set up by a 35-yard Miller-to-Fields pass on which the Boilermakers blew the coverage.
Purdue answered by retaking the lead on TerBush's quick pass to the right flank where Bush picked up a key block from Crosby Wright while racing untouched 31 yards for the score and a 20-14 lead.
The Boilermakers defense had been ravaged in its last two outings, both at home: a 44-13 loss to Michigan and a 38-14 defeat to Wisconsin. It surrendered an incredible 82 points, 771 rushing yards and 1,054 yards.
But the Buckeyes, with one of the most volatile offenses in the nation, were held to 342 yards.
Still, they had life at the end -- with an unknown and almost forgotten quarterback.
Asked if this was his most devastating loss at Purdue, coach Danny Hope responded, "You said that. No."
For Ohio State, however, it was a win for the ages.
"That's one of those things that will go down in the record books forever," Heuerman said. "There's no one more deserving than Kenny, too. I love the guy. It's incredible. I get chills thinking about it."