SOUTH BEND, Ind. -- After seeing a 10-point halftime lead evaporate into a second-half deficit, Indiana State sophomore swingman Khristian Smith recalls thinking one thing.

"We've just got to fight back," Smith said Sunday after the Sycamores upset 21st-ranked Notre Dame, 83-70. "Runs are going to happen."

For the Sycamores, it was an ensuing run of their own that determined the outcome. After falling behind 45-44 with 15:07 remaining, Indiana State produced a spurt in which it outscored the Irish 18-3 to take control of the game. The Sycamores improved to 2-1 while the Irish dropped to 2-1.

With his team trailing on the road, Indiana State coach Greg Lansing was not concerned with his team losing its confidence.

"That's one thing I don't have to worry about," Lansing said. "They think they're pretty good."

On Sunday, the Sycamores were good, and balanced. Five Sycamores scored in double figures, led by Justin Gant's 17 points and Smith's 15. Manny Arop chipped in 13 while Jake Odum and Devonte Brown each added 10.

Notre Dame was led by Eric Atkins' 18 points while Jerian Grant added 17 and Pat Connaughton 16. No other Irish player scored more than six points. Notre Dame shot 37 percent (28-of-58) from the floor, and committed 16 turnovers, many of them in the first nine minutes of the game.

"We got beat by one heck of a basketball team today," said Irish coach Mike Brey, who suffered his first November home loss in 14 years at the school. "I think their veteran poise was better than our veteran poise. It was Indiana State imposing their will on us on both ends of the floor."

The Sycamores built their halftime lead thanks to a 12-0 run. Smith scored eight points during the spurt, starting it with a dunk and adding in a 3-pointer.

The Irish, however, surged ahead when Austin Burgett completed a three-point play with 15:07 remaining.

Indiana State responded.

"We don't want to go back to Terre Haute with that loss, having that lead at halftime. What we went through Thursday, we knew we couldn't go through again today," said Smith referencing a 96-95 loss to Belmont earlier in the week. "It was a great opportunity being up I think 10 at halftime, to let it slip. We fought and dug deep just to get that lead back and played our game the rest of the way."

Atkins wasn't surprised that the Sycamores, who beat a pair of ranked teams last season, answered ND's run with a run of their own.

"Not really. It's a game of runs," Atkins said. "We made our run and they made their run to take the lead right back. We didn't respond after that. That's what hurt us right there."