EAST LANSING, Mich. -- Shavon Shields did not think he could play in the second half on Wednesday night. Slumping Michigan State sure wishes he stayed in the locker room.

The senior Nebraska swingman was helped off the court late in the first half with a back injury, then returned with a vengeance after halftime. Shields poured in 28 points, 19 in the second half, and Nebraska won its fourth straight conference game by upsetting the No. 11 Spartans 72-71 at the Breslin Center.

Shields, who tied his season high in points while making 12 of 20 shots from the field, thought his night was over after he collided with Michigan State freshman guard Matt McQuaid.

"I honestly didn't (think he'd return)," Shields said. "I need a day off tomorrow."

Cornhuskers coach Tim Miles cautioned Shields not to overextend himself at the break.

"I just told him if you feel like you can't go, you're not letting us down. We'll figure it out," Miles said. "But boy, did he go."

Freshman point guard Glynn Watson Jr. tossed in 13 points, junior guard Tai Webster had 10 points and freshman forward Jack McVeigh added eight for Nebraska (12-8, 4-3 Big Ten), which took command by reeling off 13 straight points midway through the second half.

Shields came through on a night when the team's top offensive threat was saddled by foul trouble. Junior guard Andrew White, averaging a team-high 18 points, was held to seven points before fouling out with 1:54 left.

Senior guard Denzel Valentine's 24 points led the slumping Spartans (16-4, 3-4), who have lost three straight. Valentine missed a potential game-winning jumper at the buzzer.

Spartans coach Tom Izzo was confounded by his team's decision-making.

"In my career, I've been through a heck of a lot more than this," he said, referring to the slide. "I'm just disappointed we would lose games cerebrally, especially with some of the guys involved in it. Right now, we shouldn't be doing that."

Michigan State junior guard Eron Harris had 14 points, freshman power forward Deyonta Davis contributed 13 points and seven rebounds and center Matt Costello added eight points and 10 rebounds.

Shields quickly shook off the injury to score three baskets in the first four minutes of the second half.

Valentine's corner 3-pointer put the Spartans up 53-49 and another from the wing gave the Spartans a five-point edge.

That didn't last long as McVeigh fired in two 3-pointers as part of the 13-0 Nebraska run. Shields's three-point play with 8:35 left capped it, giving the Cornhuskers a 64-56 lead.

"We just started getting stops. We couldn't quit," Shields said of the outburst. "When you get down (five), you've just got to close the gap and make plays to get it even and that's what we did."

Nebraska won its last three by double digits, giving it a mental boost heading to East Lansing.

"We've got a lot of young guys," Shields said. "Getting confidence in them and confidence in each other is huge. Those double-digit wins helped."

The Spartans got it down to four before Shields' jump hook with 2:31 remaining. Harris drilled a 3-pointer with a 45.8 seconds left to make it 70-68. Shields answered with a 13-foot shot, but Valentine banked a 3-point while falling down to cut Nebraska's lead to one.

Webster missed the front end of a one-and-one, but Valentine's 18-foot shot in transition bounced off the rim.

"We kind of lost focus at the end," Valentine said. "We haven't been doing the little things right."

The Spartans were 12 of 21 from the foul line, another reason why Izzo thought his team let one slip away.

"That was a killer," he said. "The biggest killer was when we had a five-point lead and make some incredibly poor decisions. But I swear to God, we missed some good shots."

NOTES: The Spartans won four of the first six meetings since the Cornhuskers joined the Big Ten, but Nebraska recorded victories the last two seasons. ... Michigan State sophomore PG Lourawls Nairn Jr. missed his second game with plantar fasciitis in his right foot. ... The Spartans average 20.2 assists, ranking second nationally. ... The Cornhuskers, who won their last two Big Ten road games, haven't posted three straight conference road victories since 1998, when they played in the Big 12. ... Nebraska has reached the 90-point mark three times, matching the team's total for the previous eight seasons. ... The Cornhuskers had lost their last 10 games to ranked opponents.