MIAMI — Pat Riley's worst season as coach of the Miami Heat will be his last.

The Hall of Famer resigned as coach Monday but remains team president. Erik Spoelstra, a 37-year-old assistant, will succeed Riley and become the NBA's youngest current coach. Spoelstra has never been a head coach at any level outside the NBA's summer league.

Miami finished the season with the NBA's poorest record (15-67) and, by far, the worst of Riley's 25-year career.

"I look forward to the challenge," said Spoelstra, who received word of the decision over the weekend.

As president, Riley will continue overseeing the plan to rebuild a franchise that's just two years removed from a championship, after deciding that he'd best benefit the franchise by working exclusively from the front office.

The on-court duties now belong to Spoelstra, who started in the Heat video room in 1995.

"While we are always looking for NBA talent to perform on the court, the most important talent that you may find has to perform on the bench, in the locker room, late at night, watching film, motivating and executing all the responsibilities of a head coach," Riley said. "I believe Erik Spoelstra is one of the most talented young coaches to come around in a long time."

Riley's future was among many major issues awaiting Miami this offseason. The Heat could have the No. 1 pick in the draft, are assured a top-four pick and are certain to make moves in an effort to revamp a roster plagued by injuries.

"Pat Riley has instilled in me values that enabled me to win a championship in just three seasons," Heat guard Dwyane Wade said Monday. "I've seen him do the necessary things to make us winners and I believe that with his focus on being president and his commitment to the team, we will once again become a contender."

Wade has worked extensively with Spoelstra in practices and 1-on-1 sessions.

"I believe in Coach Spo and have complete confidence that our team will succeed with him at the helm," Wade said.

Spoelstra indicated he would like to keep assistants Ron Rothstein, Bob McAdoo and Keith Askins.

Unless he comes back — he has once before — Riley finishes his career with 1,210 victories, third most in NBA history behind Lenny Wilkens and Don Nelson. He won seven championships in all, five as a head coach, one as an assistant and one as a player, and was voted into the 2008 Hall of Fame class this month. His induction is Sept. 5.

"Today, I am definitely sure that I don't want to do this anymore," Riley said.

The rebuilding process will still be his primary focus.

Riley essentially began that job in February when he traded disgruntled center Shaquille O'Neal to the Phoenix Suns. The move not only rid the team of a player who didn't want to remain in Miami, but gave the Heat some salary-cap room that wouldn't otherwise have been available until O'Neal's contract expired in 2010.

"Regardless if Pat is coaching or not, I think he'll still have a lot of say-so in what goes on around here," Heat forward Shawn Marion, who was acquired in that trade for O'Neal, said this month.

Spoelstra came to the Heat in 1995 as video coordinator and was promoted to assistant coach/video coordinator two years later. In recent years, many team insiders considered Spoelstra as the person Riley would promote when he deemed the time was right.

That time was Monday.

"This game is now about younger coaches who are technologically skilled, innovative and bring fresh new ideas," Riley said. "That's what we feel we are getting with Erik Spoelstra. He's a man that was born to coach."

It's a tactic Riley used before. He stepped down days before the 2003-04 season began, walking into then-assistant coach Stan Van Gundy's office one morning and asking him, "You ready?"

Van Gundy remained coach for two-plus seasons, resigning 21 games into the 2005-06 campaign. Riley replaced his former protege on the bench and engineered Miami's march to the 2006 championship.

But the Heat have gone 59-105 in regular-season games since, the second-biggest two-year fall by a championship team in NBA history.

"I've worked for a great leader, a Hall of Fame coach and someone who's been a great mentor to me for 13 years," Spoelstra said. "It's been a great relationship."

Riley started his head coaching career with the Los Angeles Lakers, winning a championship in his first season with a team led by Magic Johnson and Kareem Abdul-Jabbar. He also took the New York Knicks to the NBA finals before coming to Miami in 1995, where on the day he was introduced he famously talked about envisioning a championship parade down Biscayne Boulevard.

Eleven years later, that vision became reality. And if it happens again, it'll come with Riley watching from off the court.

Riley's last game was the Heat finale on April 16, a win over the Atlanta Hawks. If he knew that would be his last time on an NBA sideline, he didn't tip his hand that night.

The final buzzer sounded, Riley waved to the Hawks' bench and walked briskly through the tunnel leading to the locker room.

No last look around, no grand gesture, just a nondescript exit to one of the NBA's most glamorous coaching careers.

"I made a point 25 years ago when I started coaching, made a point to myself and a promise to myself and more than anything else to the game that if I could never give everything I have to the game that I need to give, then I know it's time for me to step aside," Riley said.