St. Charles East had St. Joseph on the ropes the entire game.
Between its torrid shooting in the opening quarter to Dom Adduci slashing at will, the Saints led for virtually the entire game.
But the Chargers also seemed to have an answer at critical moments.
Cole Gentry converted a pair of foul shots with 79 seconds remaining in the final quarter of the last game of the Ron Johnson Thanksgiving Boys Basketball Tournament Friday night in St. Charles.
Neither team would score in regulation again, and St. Joseph had the upper-hand for much of the overtime period.
Gentry forced a final tie with his only field goal of the game, but the Chargers advanced to the championship game -- against St. Charles North -- via the free-throw line.
St. Joseph (3-0) converted 8 of 10 from the line in overtime to escape with a 71-68 victory.
The host Saints dropped to 1-2 and will face Downers Grove South in the fifth-place game.
St. Joseph scored 7 of the opening 9 points of the extra session to take a 68-63 lead.
Jake Asquini had not scored from the field since the first quarter, but the junior guard drained his third 3-pointer of the game to make it a 2-point spread.
Following a Charger turnover, Gentry drove the paint -- and after missing his first 7 shots -- banked home a 10-footer to tie the game at 68-68.
"I was a little disappointed with my shooting," said Gentry, who was making his season debut due to a lower back issue. "I needed to help out the team. At that point of the game, Dominic had already fouled out. I just focused on the (back) board."
Adduci was disqualified on fouls with 1:46 to play in overtime.
But the senior guard had put on an electrifying performance before committing his fifth foul.
Realizing his perimeter game was out of sync, Adduci slashed and burned all night, scoring a game-high 26 points and grabbing 9 rebounds.
"(Adduci is) an excellent player," said legendary St. Joseph coach Gene Pingatore, who has more victories than any boys coach in state history. "He's got a great motor. He scored a lot of points (12) on free throws. I know that."
It was by design.
"My outside shot wasn't falling," said Adduci, who had a pair of 3-point plays in the third quarter. "I felt like I had to take (the ball) to the hole. I needed to drive and draw fouls. I just needed to score some easy points."
St. Charles East hit four 3-pointers in the opening quarter, scoring 22 of the first 33 points of the game.
But St. Joseph, paced by three players -- Jordan Ash (23 points), Glynn Watson (18) and Nick Rakocevik (14) -- had 21 second-quarter points to lead 36-35 at halftime.
Asquini (13 points), James McQuillan (10) and Mick Vyzral (10) complemented the 26-point Adduci effort for St. Charles East.