Amazing what a couple of early big plays will do to boost a football team.

Also amazing: what a quintet of 70-plus-yard scoring marches will do to demoralize an opponent.

Both scenarios dovetailed Saturday at TCF Bank Stadium, as the Gophers put it all together in a 54-21 blowout of Nebraska.

Rodney Smith returned the opening kickoff 100 yards for a touchdown and quarterback Demry Croft had a 73-yard touchdown run among his 183 yards and three TDs on the ground as the Gophers (5-5, 2-5 Big Ten) kept alive their hopes for six wins and bowl eligibility.

In the process, Minnesota dropped Nebraska to 4-6 and 3-4, extending the misery for the Cornhuskers in a lost season. Maybe the Gophers didn’t get full revenge for the 84-13 thrashing Nebraska administered in 1983, but they embarrassed the proud program in front of an announced crowd of 39,993.

“We needed to start fast,’’ Gophers coach P.J. Fleck said. “We talked in the locker room that two teams who are 4-5, it’s a big game for both of them. Whoever strikes first, you can take the spirit out of somebody else.”

The Gophers rolled up 514 yards of offense, including 409 rushing. They did most of their damage in the first half, when they had 311 total yards, 238 on the ground, and bolted to a 30-14 lead. Croft put together his best game as a Gopher, also completing nine of 15 passes — two incompletions were throwaways and two were drops — for 105 yards to go along with his school-record rushing day by a quarterback.

“Demry did a tremendous job running the offense,” Fleck said.

The game began perfectly for the Gophers, when Smith returned that opening kickoff for the TD, cutting back and sprinting down the left sideline. Smith added 134 rushing yards and finished with 279 all-purpose yards.

“It parted like the Red Sea,’’ Smith said of the return.

Added Croft, “When I saw him run, it was like, ‘Oh, man. He’s gone!’ ’’

Nebraska responded to that by driving 75 yards on 12 plays and tying the score on Mikale Wilbon’s 1-yard run that was set up by Tanner Lee’s 9-yard hookup with JD Spielman to the Minnesota 13.

Then Croft led the Gophers on a 12-play, 75-yard march highlighted by an option pitch to Smith for a 7-yard gain on fourth down, a 22-yard scramble to the 3 and an option keeper for a 3-yard TD run for a 14-7 lead with 3:08 left in the first quarter.

Nebraska had another response, moving to the Gophers 6 and facing fourth-and-1 two plays into the second quarter. But Gophers safety Duke McGhee stuffed Wilbon for a 1-yard loss, swinging momentum. “That’s a result-ending, changing-type play,” Fleck said. “That was tremendous.’”

Five plays later, Fleck could say the same thing about Croft, who executed a beautiful option fake to Kobe McCrary, then sprinted 73 yards up the middle for a TD and a 20-7 Gophers lead with 11:42 left in the half. The extra point failed because of a bad snap.

“It was amazing what he did,’’ Smith said of Croft. “When you have a quarterback who is dangerous like that, it makes things easier for the running backs.’’

McCrary, who gained 93 yards rushing, scored the first of his three TDs on an 11-yard run with 6:40 left in the half, and Emmit Carpenter kicked a 36-yard field goal with 4 seconds left in the half for a 30-14 lead. Nebraska’s other first-half TD came on a drive in which Spielman, the redshirt freshman and former Eden Prairie standout, caught four passes for 66 yards.

In that decisive first half, the Gophers had scoring drives of 75, 93, 72 and 71 yards, with the first three being for touchdowns and the last for a field goal.

In the second half, Nebraska replaced Lee, who suffered what coach Mike Riley termed an “impact migraine,’’ with Patrick O’Brien. The Gophers defense held strong, limiting the Huskers to a TD early in the fourth quarter.

“Their demeanor changed a lot and their passion changed a lot,’’ Gophers safety Jacob Huff said of Nebraska. “That’s something you notice as a defensive player.”

Meanwhile, McCrary had TD runs of 9 and 43 yards. In between was Croft’s 1-yard TD run after the QB’s 64-yard gain.

It all added up to 54 points, and it was a far cry from last week’s 33-10 loss at Michigan, in which the Gophers were dominated. This time, they did the dominating.

“We got better,’’ Fleck said. “… Last week, like I said, we got whupped. This week, we got better.”