Winston had 21 points and Tillman scored 19, leading the 14th-ranked Spartans to a 76-56 win over Illinois on Thursday night.
Winston, who missed the previous game to rest a banged-up knee, controlled the tempo of the game and had six assists.
"Magic (Johnson) is the best point guard to ever play here and that young man is probably the next best," Illinois coach Brad Underwood said.
Tillman was pretty good, too, when the Michigan State resumed Big Ten play. He had seven rebounds, a career-high six assists and a season-high four blocks.
"Xavier's all-around game was unbelievable," Michigan State coach Tom Izzo said.
The Spartans (11-3, 3-0 Big Ten) are on a six-game winning streak and have won their first three conference games to stay alone in first place.
Michigan State was in control from the outset but had just a six-point edge at halftime. The Spartans pulled away early in the second half with a 15-3 run.
"There were times in that game we played as good as we played all year," Izzo said.
The Fighting Illini (9-4, 1-2) lost a lopsided game in the Big Ten for the first time this season. They had a one-point loss at then-No. 3 Maryland and beat then-No. 5 Michigan by nine points last month.
Illinois' Ayo Dosunmu scored 13 of his 18 points in the first half and Alan Griffin finished with 17 points. Freshman center Kofi Cockburn, who entered the game averaging a team-high 16 points, had five points on 2-of-10 shooting.
"Tough night for Kofi," Underwood said. "He'll bounce back."
Gabe Brown scored 12 points and Aaron Henry added 10 points for the Spartans. Marcus Bingham didn't score but led the defensive effort against Cockburn and had a career highs with 12 rebounds and five blocks.
"I was really impressed with Bingham and the job he did on both ends of the court," Underwood said.
Michigan State led Illinois 36-30 after a feisty, foul-filled first half.
Both teams had a key player, Winston and Cockburn, limited by foul trouble and combined to have seven players called for two fouls in the opening 20 minutes.
Underwood was called for a technical for arguing with officials in the first half. He nearly was called a second technical after Trent Frazier was whistled for a block when he appeared to draw a charge on Kyle Ahrens' 35-foot heave just before the half.
"I got a 24-hour moratorium before I can call the league office to ask about that," Underwood said.
Illinois: Underwood averaged 13 wins during his first two seasons and should be able to surpass that clip with his physical team, which has three players averaging double digits.
"I feel great about where we're going," Underwood said.
Michigan State: The preseason No. 1 team had the kind of balanced contributions it will need to live up to expectations.
"We're definitely growing," Tillman said. "We're learning how to make a lot of momentum plays. We had a couple of key stops in the second half and blew the game open.
The Spartans can make a jump in the poll if they also win against No. 12 Michigan.
Ahrens, whose career has been stunted by injuries, left the court in the second half and went toward his team's locker room. He returned to the court, but did not play after having a point and a rebound in nine minutes. Izzo said the senior forward aggravated his Achilles tendon injury.
Illinois: Hosts Purdue on Sunday night.
Michigan State: Plays the rival Wolverines on Sunday at home.
"I'm going to enjoy one more hour and then I'm going to start working on my next opponent," Izzo said.
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