Denver ? George Karl had been involved with basketball since the seventh grade, so not having it in his life for nearly two years left him feeling empty.

Now that he’s headed back to the NBA, Karl has a greater appreciation for what the game has meant to him.

Out of the NBA since the Bucks fired him in 2003, Karl was back in Milwaukee on Thursday to take over as coach of the underachieving Denver Nuggets. He’s expected to be on the bench tonight, making his debut with the Nuggets against his former team.

“The last 18 months was the first time I was not with a basketball team for 38 years,” Karl said. “I now realize how fun and what a privilege it is to be with a basketball team.”

The Nuggets hope his enthusiasm rubs off.

One of the favorites in the Western Conference at the start of the season, Denver hasn’t lived up to the expectations that came with adding All-Star power forward Kenyon Martin to a team that had reached the playoffs for the first time in nine years.

Plagued by injuries and inconsistencies, the Nuggets got off to a horrible start and haven’t really recovered. Coach Jeff Bzdelik lost his job Dec. 28 and Denver has been only marginally better under interim coach Michael Cooper, entering tonight’s game 17-25 and 121/2 games out of first place in the Northwest Division.

Karl brings plenty of credibility, ranking 13th all-time with 708 wins and leading his teams to five division titles and 13 playoff appearances in 16 seasons.

He has also had experience turning around underachieving teams.

Karl helped Seattle reach the playoffs in 1991-92 after a 20-20 start cost coach K.C. Jones his job, and led the Sonics to three 60-win seasons in five years, including a trip to the 1996 NBA Finals.

“He’s clearly one of the best coaches in the NBA, has always been so and his record exhibits that,” Nuggets GM Kiki Vandeweghe said. “We are very excited to have him with us.”

Karl can be feisty and confrontational, but it might be just what the Nuggets need.

With a lineup that includes Martin, Carmelo Anthony, Andre Miller and Marcus Camby, Denver certainly doesn’t lack talent. What the Nuggets seem to need is motivation.

Things got better under Cooper, who will stay on as an assistant, but Denver still only won four of 14 games and had trouble closing out the close ones.