For the cold-shooting Badgers (23-12), the upset loss snaps a string of six straight first-game victories. Ole Miss (27-8) trailed 25-22 at halftime in the second-round game and Henderson, who led the Southeastern Conference with 20 points a game, had only two points on one-for-11 shooting.
But the flamboyant and outspoken guard found his touch just in time for Ole Miss.
His back-to-back 3-pointers tied it 36-36 and his layup and two free throws in the final minute sealed the win.
Reginald Buckner had nine points and 12 rebounds for the Rebels, who held Wisconsin to miserable 25.4 percent from the field. Sam Dekkar had 14 points for Wisconsin, which was only 15 for 59, including 7 for 30 from beyond the arc.
In the third round of the West Regional on Sunday, the Rebels will play either No. 4 seed Kansas State or No. 13 La Salle.
Henderson’s futility reached its zenith with about 12 minutes to go when he fumbled the ball in the Wisconsin back court right into the hands of Dekkar, who raced down the court with Henderson on his shoulder and laid the ball in for a 36-30 Badger lead.
But on Ole Miss’ next possession, Henderson finally connected after missing his first six 3-pointers and all but one of his first 13 from the floor.
After Buckner missed two free throws and the Rebels rebounded an errant Wisconsin shot, Henderson hit another 3-pointer before Jared Berggren answered for the Badgers with a 3 of his own.
Murphy Holloway put the Rebels ahead to stay with a tip-in and another bucket.
Then, after one of Wisconsin’s 11 turnovers, Jarvis Summers connected for Ole Miss.
Henderson, whose 88 percent foul shooting led the SEC, hit two free throws at the 5:13 mark for a 45-41 lead, then the two teams swapped turnovers before Buckner pulled down a defensive rebound and Henderson canned a jumper for a 47-41 lead.
An unsightly first half ended, appropriately, with a Wisconsin turnover and a 25-22 lead for the Badgers.
FLORIDA GULF COAST 78, GEORGETOWN 68
PHILADELPHIA — Sherwood Brown scored 24 points and Bernard Thompson had 23 to lead Florida Gulf Coast to an incredible NCAA tournament debut, a 78-68 win over second-seeded Georgetown.
The Eagles, in their second season of being eligible for Division I postseason, became just the seventh No. 15 seed to beat a No. 2.
FGCU (25-10) will play the winner of the game between seventh-seeded San Diego State and No. 10 Oklahoma in the third round on Sunday.
NORTH CAROLINA 78,
KANSAS CITY, Mo. — P.J. Hairston scored 23 points, James Michael McAdoo added 17 and North Carolina unleashed a flurry of 3-pointers to subdue gritty Villanova.
The never-say-die Wildcats (20-14) erased a 20-point deficit that North Carolina built in the first half and then nearly climbed out of a nine-point hole in the final minutes after the Tar Heels hit three consecutive 3s and once again appeared to take control.
FLORIDA 79, NOTHWESTERN STATE 47
AUSTIN, Texas — Erik Murphy had 18 points to lead four Florida players in double figures and the Gators shut down the NCAA’s highest-scoring team.
No. 3 seed Florida turned this one into a rout with a 19-1 run in the second half and held the 14th-seeded Demons (23-9) to their fewest points this season — 34 below their average.
INDIANA 83, JAMES MADISON 62
DAYTON, Ohio — Freshman Yogi Ferrell scored 14 points in the first six minutes as top-seeded Indiana slam dunked its way past James Madison.
Not taking any chances with a No. 16 seed, the Hoosiers (28-6) started fast and built a 33-point lead in the second half over the Dukes (21-15) and opened the tourney with a statement they intend to be around for a while.
TEMPLE 76, NORTH CAROLINA STATE 72
DAYTON, Ohio — Khalif Wyatt scored 31 points, finishing the game with an injured left thumb that had him grimacing before his clinching free throws, and Temple broke with its one-and-done NCAA tournament trend.
The ninth-seeded Owls (24-9) opened a 17-point lead before Wyatt — the Atlantic 10’s player of the year and top scorer — hurt his left thumb and left the game briefly, returning with black tape on the non-shooting hand.
MIAMI 78, PACIFIC 49
AUSTIN, Texas — Durand Scott had 21 points and Miami had a triumphant return to the NCAA tournament.
The Hurricanes (28-6), who may be even better than their No. 2 seed in the East Regional would indicate, put the game out of reach with a 14-0 run midway through the first half of their first NCAA tourney game in five years.
ILLINOIS 57, COLORADO 49
AUSTIN, Texas — Brandon Paul and D.J. Richardson made consecutive 3-pointers to give Illinois back the lead with 6 minutes left and the seventh-seeded Illini pulled out a tough win over Colorado.
Illinois led by 16 at halftime only to watch Colorado rip off a 21-2 run in the second to grab the lead. The Illini looked desperate until Paul and Richardson coolly knocked down their shots to put Illinois ahead 48-44.
DUKE 73, ALBANY 61
PHILADELPHIA — Seth Curry scored 26 points, Mason Plumlee had 23 and second-seeded Duke beat Albany.
The Blue Devils (28-5) will meet seventh-seeded Creighton in the third round Sunday.
CREIGHTON 67, CINCINNATI 63
PHILADELPHIA — Doug McDermott had 27 points and 11 rebounds, and Gregory Echenique scored 13 points to help Creighton hold on.
Ethan Wragge added 12 for the Bluejays, who won their NCAA tournament opener for the second straight year.
LA SALLE 63, KANSAS STATE 61
KANSAS CITY, Mo. — Jerrell Wright made three foul shots in the final 30 seconds, and No. 13 seed La Salle advanced after blowing an 18-point halftime lead to beat fourth-seeded Kansas State.
Wright, who scored a game-high 21 points for the Explorers (22-9), made the first two free throws to give La Salle a 62-61 lead. Kansas State’s Jordan Henriquez missed in the paint at the other end, and Wright made the first of two more free throws with 9.6 seconds to go.
OHIO STATE 95, IONA 70
DAYTON, Ohio — Sam Thompson had career highs with 20 points and 10 rebounds, part of a dominating performance by Ohio State’s front line against Iona.
The second-seeded Buckeyes (27-7) have won nine straight, including their last five games of the regular season and a run to the Big Ten tournament title.
San Diego State 70,
PHILADELPHIA — Jamaal Franklin scored 21 points, James Rahon had 17 and San Diego State beat Oklahoma 70-55 on Friday night to earn its third NCAA tournament victory.
The seventh-seeded Aztecs (23-10) will play No. 15 seed Florida Gulf Coast on Sunday in the South Regional.
The Eagles introduced themselves to the college basketball world with a 78-68 win over Georgetown.
Iowa St. 76, Notre Dame 58
DAYTON, Ohio — Freshman Georges Niang matched a season high with 19 points and Iowa State, showing it can do much more than just fire away from outside the 3-point line, dismantled Notre Dame 76-58 on Friday night in the NCAA tournament.
The 10th-seeded Cyclones (23-11) will play No. 2 seed Ohio State on Sunday. The Buckeyes advanced with a 95-70 thrashing of Iona.
Kansas 64, Western Kentucky 57
KANSAS CITY, Mo. — Jeff Withey scored 17 points and top-seeded Kansas struggled to put away scrappy Western Kentucky in a 64-57 victory Friday night that avoided what would have been the biggest upset on a day full of them in the NCAA tournament.
The Jayhawks (30-5), flummoxed by the Hilltoppers' full-court pressure, trailed 31-30 at halftime. Kansas eventually built an 11-point lead in the second half, but couldn't put Western Kentucky away until Ben McLemore's two foul shots with 11 seconds left in the game.
Minnesota 83, UCLA 63
AUSTIN, Texas — Andre Hollins scored 28 points and Minnesota rolled past punchless UCLA 83-63 on Friday night in the second round of the NCAA tournament, a game that could be Bruins freshman Shabazz Muhammad's last in college and coach Ben Howland's final one leading the program.
Austin Hollins scored 16 for the 11th-seeded Gophers (21-12), who advanced to Sunday's third round against No. 3 seed Florida in the South Regional. The Gophers eased some pressure on coach Tubby Smith by giving him his first NCAA tournament win in six seasons.