Haughn tied an NCAA record by making eight 3-point shots in as many attempts as the Flyers, now 5-14, shocked the Billikens, who were 19-1 and rated 17th in the latest Associated Press poll.
After trailing by 20 points (33-13) with 6:03 remaining in the first half, the Flyers made a great comeback to win their first Great Midwest Conference game against the team which held first place.
"Shawn Haughn was unbelievable the entire game," UD Coach Jim O'Brien said. "He was perfect from the 3-point line. He can shoot that well, and he was crazy hot tonight.
"I'm just happy for all our players. We needed this one. They worked real hard. Everybody was a hero tonight."
Although he was scoreless for the first 17:32, the 6-foot-3 Haughn more than doubled his previous high of 14 points. He made 9 baskets in 13 attempts and was 4 for 5 at the free throw line.
His 30 points is the most ever scored by a UD freshman, breaking the old record of 26 set by Jim Rhoden in a 1978 NIT game against Fairfield.
"Shawn had an awesome game," said co-captain Alex Robertson, who scored 18 points - all in the second half - and scored six of Dayton's 10 points in the overtime. "It couldn't happen to a better player."
"It feels good to finally prove to everybody that we are a good basketball team and we can compete with anybody in the nation," Haughn said. "I think everybody on our team feels that way. We've known we've been a good basketball team all along. We haven't done the little things to pull out a win. I think every game so far we've gotten down 10 or so and we've fought back. Then we run out of gas. Today we found that killer instinct to get over the top and put a team away."