With a chance to claim sole possession of first place in the Big Ten, the Spartans came out flat and were outplayed by the Huskers in a 60-51 loss in East Lansing.
"We did what non-championship teams do," Izzo said. "We did not bring it. We did not defend. We did not play smart and we did not play with the toughness that most of our teams play with."
Comparing Nebraska to some of his former teams at Michigan State, Izzo said Tim Miles' bunch were "junkyard dogs" with their toughness Sunday.
"They took it at us," he said. "They walked it, they talked it. They played it."
The Spartans shot a season-low 34 percent from the field and while Nebraska shot just 35.8 percent, it was timely shooting from Huskers guard Terran Petteway that was the difference. The sophomore scored 14 of his game-high 23 in the final nine minutes.
"You do gotta give Pettaway some credit," Izzo said. "He made some big-time (shots). Every one of his 3s, I think, was toward the end of the shot clock, going right or falling away. …
"It was their night. Their night started at the beginning.
Eight seconds into the game, Nebraska forward Walter Pitchford – a Michigan native – hit a 3-pointer. The shot ignited the Huskers as they hit four of their first five shots, including three 3-pointers – an 11-4 start Izzo called a punch in the mouth.
"Those guys came out and did what we said we were going to do to them," said Spartans point guard Keith Appling, who saw his first action after missing three games with a wrist injury.
"They came out there aggressive on both ends of the floor, made some things happen, made some big-time shots and they were successful by doing that."
Michigan State sophomore guard Gary Harris, who led MSU with 17 points but was just 1 of 7 from 3, said it was a shock early.
"They came out with more energy and they came out and saw a few shots go down early," he said. "They got the confidence early and they had it the whole game."
As the Huskers opened strong, the Spartans missed four layups in the first 7:40.
""I sat there and watched a team shrivel up with a couple of bad plays," Izzo said.
The Spartans fought back and held a two-point lead at three times in the first half, but never led after Pitchford hit a 3 with 5:48 before halftime.
A Ray Gallegos layup put Nebraska ahead by 11 early in the second half, but the Spartans stuck around. Whittling away at the Huskers' lead, Michigan State was within four points five times in the final 11:07.
But every time the Spartans got close, it was Pettaway coming up with an answer. The sophomore transfer from Texas Tech hit three 3s in the final 8:22 – two in the final 4:42.
"It just felt like he was unstoppable," Michigan State senior forward Adreian Payne said. "It just seemed like he could throw up anything and it would go in.
"We didn't have an answer for it."
The Spartans got within two after Payne hit a basket in the post with 4:01 to go, but again it was Petteway doing the Spartans in with a big shot as he hit a straight-away 3 over MSU guard Denzel Valentine.
Two Harris free throws pulled MSU back within 3 and they had a chance to take the lead when Pettaway missed a 3 with 1:21 to go, but Payne missed a transition layup.
"I was thinking I should go for the dunk, but when he came up under me I tried to finger roll and guard myself on the way coming down so I wouldn't get hurt," Payne said.
The loss kept Michigan State in a tie atop the Big Ten with Michigan, which lost 75-62 to Wisconsin on Sunday afternoon. The two teams will meet next Sunday in Ann Arbor.
‘There's always tough losses in the season," Izzo said. "This is the toughest so far because I was so disappointed in how we came out.
"On the other side of it, I'm not upset about the loss because we got exactly what we deserved."