Advance watched an 18-point fourth-quarter lead slowly disappear until a basket by Kelly's Brandon Ayers pushed the Hawks out front, 75-74 with 21 seconds remaining.
Advance went to James Master to answer Kelly, and the 6-4 center calmly moved to the top of the circle and banked home a jumper to regain the lead (76-75) for the Hornets and send the home crowd into a frenzy.
But, with seven seconds remaining, Advance's defense broke down and allowed Kelly to quickly break through its token press and find Deason all alone for a easy lay-up and the win.
"In that situation, in high school, a lot of kids are so anxious to guard the basketball that people run to the ball," Kelly coach Cory Johnson said of the deciding play of the game. "We're blessed to have a couple of kids that can see the floor well and know how to play basketball. Kendal (Deason) wanted the ball and got the ball and he finds Kent (Deason) for an easy lay-up . You just can't ask for or draw it up better than that."
Advance was without the services of senior playmaker Tyler Bowman who is awaiting the results of a MRI on his knee to determine if he'll be able to play again this season. Without Bowman's ball-handling late in the game, Advance was unable to stave off the late surge by the Hawks.
"We definitely did," Advance coach Joe Shoemaker said when asked if he felt this one got away from him. "You have a 13-point lead going into the fourth and you end up losing by one, you definitely feel like you let one slip away.
"We didn't shoot real well from the free-throw line, I think we were 16-of-29," he added. "You know, you lose by one, and coach (assistant Jacob) Sutton and I were talking that there are so many things you can look back on and you can pick one or two things that could have easily went the other way.
"We'll be glad to get all our starters back on the floor and get everybody healthy," Shoemaker said. "We haven't had our five starters from the summer on the floor together yet."
Advance (7-3) led after every quarter and when Jordan Seabaugh (11 points) opened the fourth with a 3-pointer for a 62-46 advantage and Masters (19 points) scored a deuce, the Hornets had their biggest lead of the night at 18 points, 64-46, and looked to be in total control of the game with 6:57 remaining.
Kelly, one of the hottest teams in the area of late, went on to outscore Advance 31-12 to finish the game and earn the team's eighth win against three losses.
Kelly entered the game fresh off a stellar performance at the seMissourian Christmas Tournament where they defeated Charleston and Scott City before falling in overtime in the championship game to Jackson, ranked fifth in Class 5.
Advance's Jeremy Limbaugh led all scorers in the game with 22 points before fouling out with 3:18 remaining in the game.
Limbaugh's fifth foul came on a 3-pointer by Derek Felter and resulted in a rare four-point play.
Advance will next be in action Friday night at home when the Hornets will host the Bernie Mules.