Monty Williams has reached an agreement to become the top assistant under Oklahoma City Thunder coach Billy Donovan, league sources told Yahoo Sports.

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For Donovan, who is transitioning from the University of Florida to the NBA, the securement of Williams stands as the first significant coup of his regime.

After winning 45 games and reaching the Western Conference playoffs this season, Williams was fired as New Orleans Pelicans coach last month.

Donovan and Thunder general manager Sam Presti targeted Williams and sold him on a prominent role on the staff. The Thunder have championship aspirations with a core of Kevin Durant, Russell Westbrook and Serge Ibaka, and playing a part in helping Oklahoma City into a deep run in the postseason could become a springboard for Williams, 43, to ascend into another head coaching job.

After winning 46 games in his first season with Chris Paul on his roster in 2010-’11, the gutted Pelicans made incremental improvements of 21, 27, 34 and finally 45 victories this season. Williams navigated a distressed roster of injuries and a flawed roster to deliver the Pelicans to the Western Conference playoffs. New Orleans earned the eighth seed, and lost to eventual Western Conference champion Golden State in four games.

Under Williams, star Anthony Davis developed into one of the NBA’s dominant talents. Williams is a member of Mike Kryzyzewski’s coaching staff with Team USA. Williams had a nine-year NBA career, after starring at the University of Notre Dame.

Donovan will keep Oklahoma City assistant Mark Bryant and Darko Rajakovic on staff, and likely make former Alabama coach Anthony Grant his No. 3 assistant coach, league sources said. The Thunder are still searching for an assistant coach with a strong defensive pedigree, sources said.