McGuirl, who scored 12 points in the second half, converted a four-point play with 7:13 remaining to push the margin into double-digits. The Wildcats (23-11) also used sticky defense to give sixth-year coach Bruce Weber a first-round win for the first time in four NCAA appearances with Kansas State.
Kansas State will play UMBC on Sunday after the No. 16-seed Retrievers stunned top-seed Virginia, the first time a No. 16 ever beat a No. 1 in the tournament.
Creighton senior guard Marcus Foster, who played his first two collegiate seasons for Weber's Wildcats before transferring and becoming a All-Big East pick, was limited to just five points on 2-for-11 shooting.
Foster missed his first five shots before driving for a layup with 10:31 remaining. When he came out in the final minute, Foster hugged Weber before heading to the Creighton bench.
The Bluejays (21-12), who tied for third in the Big East behind No. 1 seeds Villanova and Xavier, were led by freshman guard Mitch Ballock with 16 points and eight rebounds. Creighton shot just 33.8 percent from the field.
Foster, who came in averaging 20.3 points, was guarded mostly by Kansas State junior guard Barry Brown, who also scored a game-high 18 points. Junior guard Kamau Stokes netted 11 points for the Wildcats, who owned their largest lead (16) after the final media timeout.
The Wildcats played without All-Big 12 forward Dean Wade. The 6-10 sophomore, who averaged team-highs in points (16.5) and rebounds (6.3), was still hobbled by a stress fracture in his left foot, an injury he suffered in a quarterfinal victory at the Big 12 Tournament.
Kansas State led throughout the first half, building its lead to nine, 25-16, with a lob to sophomore forward Xavier Sneed for a dunk in transition.
Creighton cut the margin to three on a 3-pointer by Ballock with nine seconds left, but McGuirl answered with a trey at the buzzer for a 32-26 halftime lead. The Bluejays shot just 34.4 percent in the first half and were led by Mintz with eight points.
The Wildcats also did not place a first-half scorer in double figures as Stokes and freshman guard Cartier Diarra scored seven each.
--Field Level Media
Kansas State | Creighton | |
Barry Brown 18 | Scoring | Mitch Ballock 16 |
Barry Brown 3 | Assists | Khyri Thomas 4 |
Barry Brown 6 | Rebounds | Mitch Ballock 8 |
Barry Brown 7 | Free Throws Made | Mitch Ballock 2 |
Barry Brown 2 | Steals | Khyri Thomas 3 |
Barry Brown 2 | Blocks | Ronnie Harrell Jr. 2 |
Team | Points | FG% | 3PM-3PA | FTM-FTA | Assists | Rebounds | Blocks | Steals | Turnovers |
Kansas State | 69 | 46.0 | 9-19 | 14-25 | 12 | 31 | 5 | 6 | 11 |
Creighton | 59 | 33.8 | 9-34 | 4-5 | 12 | 41 | 3 | 6 | 13 |