COLUMBUS, Ohio (AP) -- Ohio State's season will end where it started.
The Buckeyes (22-13) advance to meet Mississippi (24-10) in the NIT semifinals at New York's Madison Square Garden on Tuesday. The Rebels beat Virginia Tech 81-71 earlier Wednesday night.
Ohio State won three games in the NIT Season Tip-Off before losing to Texas A&M 70-47 in the championship game at the Garden on Nov. 23.
The game was played before a loud, capacity crowd of 19,049 at Value City Arena, with Dayton fans making up at least a quarter of those in attendance. It was the sixth-largest crowd to ever witness the Flyers play and was the biggest they have played in front of in 13 years.
Brian Roberts had 20 points and Chris Wright 12 for the Flyers (23-11), who were trying to make their first trip to the NIT semifinals since 1968. Their resume included wins over NCAA-tournament teams Pittsburgh and Louisville, the latter on the road.
Koufos hit 9-of-11 shots from the field including his only 3-point attempt. He also made both free throws and had five rebounds, an assist and a blocked shot.
Butler, a first-team All-Big Ten player averaging 15 points a game, had just three in the first half but did contribute six assists. He joined with Koufos to lead the Buckeyes on a decisive spurt.
Down 31-30 at the break, the Buckeyes took the lead early in the second half and then pulled away, at first by going inside to Koufos and later by kicking passes out for 3-pointers or slashing through the lane.
With Ohio State ahead 36-35, Diebler hit a 3-pointer on a pass back outside from Koufos before Koufos followed a Dayton miss with two foul shots. Butler was on a break when his alley-oop pass was batted up in the air by Roberts. Butler leaped high to catch it, then drove to the basket and hit a left-handed layup to push the lead to 43-35.
Dayton's Wright ended a 3-minute scoring drought with two free throws before Diebler, shooting 29 percent behind the arc on the season, hit another 3 and Butler came off a pick unchallenged and hit a 3 of his own for a 49-37 lead with just under 12 minutes left.
The Flyers never got closer than nine points again.
With three 3-pointers in the opening half, Roberts passed Tony Stanley's school record of 291 3-pointers made.
The teams had not met since trading home-and-home games in the late 1980s.
The game was played on the anniversary of Ohio State's only previous NIT championship. Dennis Hopson had 26 points and Brad Sellers 17 in the Buckeyes' 73-63 win over Wyoming in the 1986 title game.