CHAMPAIGN, Ill. (AP) -- For long stretches Thursday night, Michigan State coach Tom Izzo was sure his Spartans were dogging it.
Looking flat and struggling to find a rhythm, Michigan State (No. 18 ESPN/USA Today, No. 17 AP) trailed Illinois by as many as 10 points in the first half and had no answer for center Shaun Pruitt's 6-foot-10 frame in the lane.
Turns out the Spartans weren't flat, but ill. But they found a way to overcome Illinois and illness to get a road win, 59-51.
"We had some guys getting sick there during the game," Michigan State coach Tom Izzo said, saying he only found out about problems with forward Raymar Morgan -- the team's top scorer this season -- and guards Kalin Lucas and Durrell Summers. He wasn't sure just what was wrong.
"I don't know," Izzo said. "They're all throwing up."
What the ailing Morgan couldn't provide, senior guard Drew Neitzel did. He overcame a slow start to score 17 points and lead the Spartans.
Illinois led most of the first half. But Michigan State (24-7, 12-5 Big Ten) took its first lead with 2:29 left in the first half on a layup by Neitzel, 31-29, and never trailed again.
"I thought we had a pretty good game out of Neitzel considering he was guarded by one of the best defensive players," Izzo said, referring to Illinois guard Chester Frazier.
Spartans center Drew Naymick added 12 points, including a pair of key second-half jump shots that helped bury Illinois.
The Illini (12-18, 4-13) were led by Pruitt's 13 points and six rebounds.
The teams were tied 31-31 at the half, but the Spartans pulled away early in the second half. The 6-foot-10 Naymick hit back-to-back jump shots to open the half and build a 35-31 lead.
"That first five minutes of the second half was just a killer for us," Illinois coach Bruce Weber said. "[Naymick] hits two in a row there, Neitzel gets a 3.
"Now it's a seven-point run," the exasperated Weber said, "and we're chasing them."
After trailing 23-13 with 9:25 left in the first half, the Spartans outscored the Illini 29-13 over the next 17:42.
Neitzel, who didn't score for the first 6 1/2 minutes, found just enough scoring touch to drive Michigan State. He was a cool 5-of-13 from the field, but three of his field goals were from 3-point range.
Illinois closed within three points with just over seven minutes left in the game. But Neitzel drained a 3 less than 20 seconds later to open the Spartans' lead back to six points.
The loss had a familiar refrain for Illinois.
The Illini have been a first-half team all season, and they've struggled to score in the second half of games.
On Thursday, Illinois was just 6-of-19 from the floor in the final 20 minutes.
"Like most of the season," Weber said, "when you don't shoot the ball well and don't make free throws it hurts you."
Neitzel had a hand in shutting down Illinois' outside shooting, too. Illini point guard Demetri McCamey had just three points.
"They hit a couple tough shots in the first half but we did a pretty good job on them, especially in the second half," Neitzel said.
Illinois forward Brian Randle, who Weber last week said he expected would miss the rest of the season with a shoulder injury, entered the game in the second half. The oft-injured senior finished with seven points in 10 minutes.
Michigan State will end the regular season Sunday at Ohio State before the Big Ten tournament starts next week.
The Illini close the regular season at home Saturday against Minnesota.