Outhustled on both ends of the court by the athletic Redbirds through 20 minutes while adjusting to playing without injured starting point guard Tyler Ulis (elbow), the Wildcats (7-0) emerged from halftime more physical and used that energy to gain some breathing room.
Outrebounded 20-12 in the first half, Kentucky beat Illinois State (3-5) 27-17 on the boards and held the Redbirds to 29 percent shooting in the second half.
The Wildcats face UCLA on Thursday in a matchup of programs with 19 combined NCAA championships.
Nearly a week after battling No. 2 Maryland close before losing 77-66, the Redbirds were just as determined against the nation's top-ranked team. Kentucky coach John Calipari was worried that would happen, especially with Ulis sidelined by the elbow injury sustained against South Florida.
Calipari insisted Ulis' injury wasn't serious but announced before the game via Twitter that the 5-foot-9 sophomore would sit out to ensure he's 100 percent, especially with the big matchup coming at Pauley Pavilion. But his concerns about how the Wildcats would respond without their floor general were well-founded in a sluggish start resulting in a 31-all halftime tie.
Despite Briscoe, Murray and Charles Matthews having ball-handling skills, all three struggled against Illinois State's pesky zone and man-to-man defenses and combined for all nine first-half turnovers leading to 10 points. The Wildcats were just as tentative on offense, showing little motion and causing Calipari to scream and stomp several times as Kentucky often played deep into the shot clock.
Lee's free throw with 10:42 left provided Kentucky's first lead at 16-15 but the Wildcats couldn't pull away from the athletic Redbirds, who outrebounded them and shut them out 11-0 in second-chance points through 20 minutes. Kentucky hurt itself with 10-of-20 free throw shooting.
The second half was slightly better as Kentucky turned the ball over just six times and began to take control in the paint and remain unbeaten even on an off night.
Illinois State: Monday's game was the Redbirds' second against the nation's top-ranked team and first since losing 97-81 to DePaul in March 1980. ... Illinois State fell to 8-2 against current SEC teams.
Kentucky: Freshman Skal Labissiere had two points and two rebounds in 16 minutes. ... Matthews fell hard on his back taking a shot in the lane in the second half but got up and walked it off before making one of two free throws.
Illinois State hosts UAB on Saturday.
Kentucky visits UCLA on Thursday night.