BLOOMINGTON – They rushed the floor for No. 1, after IU knocked off top-ranked rival Purdue 79-74 Saturday inside Assembly Hall. Here are three reasons why the No. 22 Hoosiers:

Lockdown defense

Given the opponent, the environment and the stakes, Indiana turned in what might have been its best start of the season Saturday. The Hoosiers were sharp from the opening tip, Trayce Jackson-Davis (25 points, seven rebounds) taking it away from the taller Zach Edey, and Race Thompson starting the scoring with a long 2.

But it was at the other end of the floor where the hosts did their best work. Smothering every Boilermaker not named Edey, they took No. 1 Purdue out of its rhythm and forced a flurry of costly mistakes. Turnovers led to easy runouts against a team that doesn’t like to defend in transition. Missed free throws egged on the capacity crowd, and handed Indiana a reprieve during a foul-ridden first half.

Insider:This is what IU can be, should be when it matters most the rest of this season.

IU’s good work and energy on defense cued the Hoosiers’ offense. Runout and secondary transition baskets built runs that turned into body blows. Edey got into foul trouble. Jackson-Davis shined.

Those fouls followed Indiana (16-7, 7-5) for most of the half, forcing Mike Woodson to get creative with his substitutions. But like most everything else about the half, the Hoosiers weathered that well. They fully deserved their 15-point halftime lead.

Purdue answers through Edey

Who else?

The Boilermakers (22-2, 11-2) didn’t get to No. 1 by rolling over, and they weren’t going to Saturday. They came out of the visitors’ locker room hell-bent on getting the potential Big Ten player of the year involved. Edey (33 points, 18 rebounds) saw concerted post touches on virtually all Purdue’s possessions in the first eight minutes of the second half, as a 15-point lead shrank to five.

IU took its turn to look rattled, the Hoosiers rushing possessions with unnecessarily quick shots. They missed enough open ones to leave the door ajar, and the Boilermakers pushed it open.

What at times became an Edey vs. Jackson-Davis showdown set up for a fantastic finish.

Photo finish

Arguably the game of the year in the Big Ten couldn't have ended any other way.

Purdue refused to let Indiana speed the game up or get anything easy offensively. Every time the Hoosiers tried to pull away, their rivals found an answer.

The Boilermakers got the lead as close as one, but IU kept finding an answer. Race Thompson pulled in two late offensive rebounds, made two crucial free throws and snared a steal.

In a battle of big men, a point guard made the decisive play.

Time running down on the shot clock, Jalen Hood-Schifino turned around a ball screen at the top of the key. Using his cover to block Edey from setting up a clean block, Hood-Schifino went to his right hand and spun the ball up off the backboard and into the net. His make gave the Hoosiers a five-point lead inside 30 seconds left. Indiana withstood Purdue's second-half charge, and knocked off No. 1.

Follow IndyStar reporter Zach Osterman on Twitter: @ZachOsterman.

This article originally appeared on Indianapolis Star: IU basketball vs. Purdue: 3 reasons Hoosiers beat No. 1 Boilermakers