TUCSON, Ariz. -- Nico Mannion dropped in floaters, got into the lane and whipped passes through traffic.
Josh Green drained 3-pointers, finished at the rim and played lockdown defense.
Zeke Nnaji bulled his way to the basket, knocked down midrange jumpers.
It's just the second game of the season, but Arizona's heralded freshman trio is playing as advertised.
Mannion scored 23 points, Green added 20 and Nnaji had 19 in No. 21 Arizona's 90-69 rout over Illinois on Sunday night.
"The three freshman were spectacular tonight in their second game," Arizona coach Sean Miller said. "Each of them were really, really good."
Arizona (2-0) was good at both ends, shooting 56% while nabbing 14 steals. The Wildcats turned a tight game at halftime into a rout with a 17-2 second-half run behind Mannion, Green and Nnaji.
Nnaji made 9 of 12 shots, Mannion had nine assists and Green was 4 for 7 from 3-point range.
"Everyone played sound tonight," Mannion said. "We had four, five guys in double digits and the guys who weren't in double digits were doing their thing, locking up on defense, making the right plays."
Illinois (2-1) was able to hang with the Wildcats in the first half of a high-level game with more than two dozen NBA scouts on hand.
The Illini went cold in the second half and struggled holding onto the ball, turning it over 22 times.
Ayo Dosunmu led Illinois with 15 points and Trent Frazier added 14.
"It doesn't matter what offense we run, we're finding way to turn the ball over," Illinois coach Brad Underwood said. "Arizona doesn't pressure. They let you just run your stuff and it's a frustrating trend."
Sunday night's game was the first big test for both teams.
Arizona used its size advantage to open the season with a blowout victory over Northern Arizona.
Illinois needed overtime to beat Nicholls State at home and blew out undersized Grand Canyon in a rowdy atmosphere Friday.
The GCU part got the Illini ready for another of college basketball's best atmospheres at McKale Center.
Illinois made seven of its first eight shots and Frazier had eight points in the first 4½ minutes.
"This is my third year, playing in these crazy environments is nothing new to me," Frazier said.
Mannion matched him, scoring on a 3, a floater, a putback and set up Nnaji for a dunk with a baseball pass in traffic .
The offensive show continued the rest of the half. Frazier had 12 points and Illinois hit 15 of 27 shots.
Mannion had 11 points, Arizona went 16 for 30 and led 39-38 on Max Hazard's last-second 3-pointer .
Arizona tightened up on defense to start the second half and went on an early 8-0 run to go up nine.
Illinois answered with a 7-0 run, but Arizona's freshman took over and the Wildcats scored 15 straight points to go up 68-52.
Illinois went 5:11 without a field goal during the run and shot 10 of 26 in the second half.
"When they went on that 15-0 run, that was pretty much game," Dosunmu said.
Illinois was long and athletic enough to hold its own against a Top-25 team like Arizona, but must cut down on the turnovers and get a better offensive flow.
Arizona's talented freshman can take the Wildcats a long way if they keep playing like this.
Illinois wasn't the only team to struggle with turnovers. Arizona had 16, including five by Mannion, that led to 15 points for Illinois.
"Sixteen turnovers are too many," Miller said. "I would say a few of them happened because it's only the second time we've played this year and we need to get used to being out there."
Kori Cockburn, Illinois's 7-foot freshman, dominated against Grand Canyon, scoring 23 points and grabbing 14 rebounds.
He was not nearly as much of a factor Sunday night thanks to Arizona's defense, finishing with nine points and seven rebounds.
"Kofi had that monster game and just dominated in the paint, we knew they were going to double team him," Frazier said. "We just didn't do a good job of pump faking and skipping it to the other side. We need to do a better job of following the game plan and executing on offense."
Illinois hosts Hawaii on Nov. 18.
Arizona hosts San Jose State on Thursday.
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