Butler didn't turn to its heralded transfer in Rotnei Clarke, or its highly-touted freshman in Kellen Dunham.
Instead the Bulldogs hung their hopes on a walk-on.
And Alex Barlow came through.
Barlow's floater in the paint with 2.4 seconds remaining lifted Butler to an 88-86 overtime upset win over top-ranked Indiana to hand the Hoosiers their first loss of the season in the Crossroads Classic.
After Indiana's Cody Zeller tied the contest at 86-86 with 23 ticks left in the extra session, the Bulldogs called timeout and Barlow got the ball on the right wing.
Using a left-handed dribble, the sophomore Barlow, who had 12 points on the season and 18 in his career coming in, drove past Jordan Hulls and into the paint before spinning back to his right and getting a friendly roll from the rim on his floater.
"I was looking for the options and they weren't open," Barlow said of the shot. "I saw the clock get about to six so I decided to make a play. I like to get to my right hand so I made a little spin move. The floater is a shot that I work on a lot, and I happened to get a lucky bounce. It was a good feeling."
Barlow finished the contest with six points.
Hulls' shot just inside the half-court line came up short at the other end.
The Hoosiers' Yogi Ferrell nailed a 3-pointer with 10 seconds left in regulation to knot the game at 76-76 and send it into overtime.
"I just knew that time was winding down, I looked at Cody and he popped out, he gave me the ball and I was open to shoot my shot," Ferrell said of his game-tying shot.
Clarke netted 19 points, Roosevelt Jones tallied 16 points, 12 rebounds and seven assists for Butler (8-2), which knocked off a No. 1 team for the first time in school history.
"It's a good confidence boost," Jones said of the win. "We already know how good we are and how good we can be."
Andrew Smith had 12 points and nine boards in the triumph, but fouled out with 1:46 left in regulation.
Zeller and Victor Oladipo poured in 18 points apiece to lead the Hoosiers (9-1), who rallied from a 71-64 deficit over the final 2 1/2 minutes of regulation to force the extra session.
Zeller sunk a pair of free throws and following a Hulls steal, Will Sheehey drew a foul and made both to make it 71-68 with 1:46 to play.
After Erik Fromm missed a jumper at the other end, Remy Abell split a pair from the stripe. On Butler's ensuing trip down the floor, Dunham, a 96.9 percent foul shooter coming into the game, made 1-of-2 to keep it a one- possession game at 72-69.
Hulls missed a triple and Abell snatched the offensive rebound and passed to Ferrell along the left wing, but the ball hit off his leg and went out of bounds with 49 ticks left.
Ferrell, though, atoned for the miscue a bit later.
Dunham, this time, made two free throws at the other end before Ferrell made a layup. Oladipo then stole the ball from Dunham and spun in for the layup to trim the margin to 74-73 with 27 seconds to play.
Barlow sunk a pair of foul shots at the other end and Ferrell got an open look for three from the right wing after Chase Stigall got lost on a give-and-go between Ferrell and Zeller. Ferrell rose up and nailed the shot with 6.1 seconds to knot the contest at 76-76.
"That's Yogi," Indiana head coach Tom Crean said of Ferrell bouncing back from the turnover. "He's got great toughness. He has great mental toughness and continues to understand how much he can improve. He's a next-play guy, and I think that's why he's such a special guard at that age."
Stigall missed a trey at the other end to send the game into an extra session, where Indiana built an 84-80 advantage, but Clarke and Stigall hit triples on back-to-back possessions for an 86-84 Butler lead with 1:02 to play.
Hulls missed a leaner at the other end, but the ball went off Butler and out of bounds and Zeller drove in the paint and finished with the right hand to square things up.
Earlier, in a nip-and-tuck first half where neither squad led by more than seven, Fromm made a trey with four seconds left in the stanza to trim the deficit to 37-33 heading into the break.
Dunham's triple with 5:54 left in the second half gave the Bulldogs their first lead, 61-59, since the 9:09 mark of the opening frame.
Stigall's 3-pointer 1:16 later capped a 16-3 run and made it 66-59.
Abell's jumper with 3:43 left cut the advantage to 67-63 and snapped a 7:41 Indiana field-goal drought.
The Bulldogs shot 47.8 percent (33-of-69) from the floor and 45.8 percent (11- of-24) from beyond the arc ... This was Butler's first win over a top-ranked team in five tries.