EAST LANSING >> For the first time all season, No. 13 Indiana trailed when it faced Michigan State. And for 18 minutes in the first half, it appeared that an upset might be in store.

It didn’t last long.

There’s a reason these Hoosiers are undefeated, and they showed why by rattling off 47 unanswered points to top the Spartans, 47-10, Saturday at Spartan Stadium.

Michigan State might have started off strong, but Indiana’s ability to find big plays on both sides of the ball made this game a blowout by the end. To add injury to insult, the Spartans also saw a number of key players go down with injuries, including quarterback Aidan Chiles and defensive back Charles Brantley.

The Spartans (4-5, 2-4 Big Ten) got out to about as good a start as anyone could ask for against the Hoosiers (9-0, 6-0), who hadn’t given up a first-quarter point in their previous eight games. Michigan State cracked that incremental shutout early with a 47-yard Jonathan Kim field goal on its opening drive. A little over seven minutes later, the Spartans led 10-0 with an 18-yard toe-tap touchdown by receiver Nick Marsh.

The key to this fast start was Michigan State’s ability to prevent those big plays on first and second down that soon wound up as its undoing. In fact, four times the Hoosiers faced third down in the first half, they wound up punting the ball.

The issue is that eventually, Indiana’s offense — second in the nation — found its groove. When the Hoosiers did find positive plays, they built on the momentum. Their first scoring drive bridged the first and second quarters, a series of screen passes and runs that stacked positive yardage before tight end Zach Horton found the end zone on a 17-yard score less than a minute into the second quarter.

That moment kicked off a second quarter that was badly lopsided. The Hoosiers outgained the Spartans 144-50 and, most importantly, outscored them 21-0. Chiles threw his second pick — to the same defensive back, Amare Ferrell — that led to Indiana’s third touchdown. The feeling of this game took a drastic turn in this span, as Indiana proved irrelevant all that a strong start meant for Michigan State.

The Spartans only faced a steeper climb when defensive backs Brantley and Malik Spencer — both sharp against the Hoosiers’ big-play receivers — went out with injuries.

Coming out of halftime with a chance to muster some sort of response, the Spartans instead watched it all spiral further out of control. Their first drive ended with a safety, two of the Hoosiers’ 12 unanswered points. As Indiana’s pass rush wreaked havoc with five sacks in the second half, it erased Michigan State’s rushing yards to a minus-24.

The Spartans’ inability to block led to another injury. Chiles was hurt after being hit while throwing the ball out of bounds. He went to the locker room before returning to the sideline with a towel over his head and did not return to the game.

Listlessly going through the motions the rest of the way, the Spartans struggled to find something, anything, to give themselves some juice. Their offensive line struggled to block, their receivers to get open, and backup quarterback Tommy Schuster to make plays.

Against Michigan State’s defense, the Hoosiers averaged 6.3 yards per play in the second half, finding them through big passing plays and physical runs with the starting offense playing until there were eight minutes left in the game — far after the game’s result was all but certain. An Elijah Sarratt touchdown, his second of the game, served as the Hoosiers’ final score, having racked up 47 unanswered points in an utterly dominant turnaround.

The Spartans’ big loss not only stings because of how lopsided this game ended, but also because of how extremely it all went downhill. Where once Michigan State had a firm chance to pull an upset, the Hoosiers’ swept the rug right out from under it. And the fall was anything but graceful.