(CNN)One of college basketball's all-time coaching greats is calling it a career.
Roy Williams, who led North Carolina to three national championships and guided UNC and Kansas to nine Final Fours, is retiring after 33 seasons as a head coach, UNC said.
"I no longer feel that I am the right man for the job," Williams said during a news conference Thursday at Chapel Hill.
Williams said that the last few seasons he felt he wasn't able to prepare his players like once did.
"I love coaching, working with kids on the court and in the locker room...I will always love that and I'm scared to death of the next phase, but I no longer feel like I'm the right man."
His 903 wins -- in 18 years at UNC and 15 at Kansas -- are the third most in men's Division I by a coach, behind only Mike Krzyzewski and Jim Boeheim.
"It's been a thrill. It has been unbelievable. I've loved it," Williams said. "It's coaching and that's all I ever wanted to do since the summer after my ninth grade year of high school."
Williams, who graduated from UNC in 1972, spent 10 years as assistant coach at North Carolina under legendary coach Dean Smith.
He then took the Kansas job in 1988 and guided the Jayhawks to four Final Fours -- including in 1991, when he beat his alma mater and mentor Smith in the semifinals but lost to Duke in the final.
Williams took over the North Carolina program in 2004 and won his first national title with the Tar Heels in 2005, with future NBA first-round picks Marvin Williams, Raymond Felton, Sean May and Rashad McCants.
His Tar Heels won two more national titles -- in 2009, with players including Tyler Hansbrough, Ty Lawson and Danny Green, and 2017, with a roster led in scoring by Justin Jackson.
North Carolina ended this season with a 18-11 record, bowing out of the first round of the NCAA Tournament with a loss to Wisconsin.
College coaches, former players across US honor Williams
UNC Chancellor Kevin M. Guskiewicz said Thursday "there will never be another coach like him."
"Nobody has loved this university like Roy Williams," Guskiewicz said.
UNC Athletic Director Bubba Cunningham said Williams' ability to run the basketball program and be so down-to-earth were "truly incredible."
UNC legend Michael Jordan said Williams "is and always will be a Carolina basketball legend."
"His great success on the court is truly matched by the impact he had on the lives of the players he coached -- including me," Jordan's statement read. "I'm proud of the way he carried on the tradition of Coach Smith's program, always putting his players first."
Mike Krzyzewski, head coach at Duke University, said in a statement college basketball "is losing one of its greatest coaches and a man who genuinely cares about the game of basketball, and more importantly, the people who play it."
"While we were on opposite sides of college basketball's greatest rivalry, we both understood how lucky we were to be part of it and always tried to represent it in the way it deserved," Krzyzewski said. "Personally, I will miss competing against him, seeing him at coaches' meetings and having the opportunity to discuss how to make our game even better."
The Duke men's basketball program also tweeted a salute to Williams.
"Salute to UNC Head Coach Roy Williams on a legendary 48-year career. All respect. Thank you for all you have done for the game, our league and the greatest rivalry in sports," Duke's tweet read.
Several college coaches offered Williams similar praise.
University of Kentucky head coach John Calipari said in a statement that what spoke to him most about Williams was the fact that "he never forgot about the people who helped get him there," which included making sure his high school coach, Buddy Baldwin, was sitting behind the bench during games.
"His ability to give credit and respect the tradition and those before him was, to me, something that always said who he was as a coach and a man. The game is going to miss his everyday presence," Calipari said.
Correction: An earlier version of this story incorrectly stated the results of the 1991 Final Four. Kansas defeated North Carolina in the national semifinals but lost to Duke in the final.