ORLANDO, Fla. -- LeBron James isn't used to playing in a nearly empty gym and it showed Wednesday.

James, who made his debut in front of 15,000 fans at the Pepsi Summer League on Tuesday, played in front of an estimated 150 people Wednesday and nearly all of them were media or coaches.

He wasn't nearly as sharp and neither were the Cleveland Cavaliers, who lost 82-78 to the Miami Heat in a game that was closed to the public. Afterward, James said he won't play the final three games of the Orlando summer league.

His agent, Aaron Godwin, said earlier that James would play Thursday against Detroit and Friday against Minnesota, but miss Saturday's finale against Milwaukee to attend a wedding back in Ohio.

James is scheduled to play some games in Boston's summer league later this month.

On Wednesday, James lost the one-on-one-battle of first-round stars.

The No. 1 pick in this year's NBA draft, who didn't play at all in the fourth quarter against Orlando on Tuesday, was in for the final 4:28 against Miami.

With Cleveland down 78-74, James made a driving layup with 17 seconds to play and was fouled. He missed the free throw, but teammate Carlos Boozer tipped it in to tie the score at 78.

James then defended Dwyane Wade, the No. 5 overall pick in last month's draft. Wade dribbled as the clock went under 5 seconds, drove into the lane and lobbed a 10-foot jumper over James to make it 80-78 with 3.7 seconds to play.

The Cavs wasted their opportunity to tie the game when Boozer was called for an offensive foul on the ensuing possession.

James had 17 points, two rebounds and three assists in 29 minutes against Miami, compared to 14 points, seven rebounds and six assists in 23 minutes the night before against the Magic.

James also committed five turnovers against the Heat, giving him eight in the two games.

"It's kind of hard to get worked up when there's not a lot of people around," James said. "You kind of like to play to the crowd, but there wasn't one."

Cleveland assistant coach Stephen Silas, who is running the Cavaliers summer league team, noticed the drop in James' intensity.

"There was so much electricity in the building (Tuesday) that you could see LeBron was really hyped up right from the start," Silas said. "He was playing on adrenaline that night, but he didn't have the same energy today. Nobody did. The loose balls, the long rebounds, the hustle plays that we were making in front of 15,000 people ... we didn't make any of those today."

Caron Butler, who made the NBA's all-rookie team for Miami last season, had 15 points while Wade had 10 points, six rebounds and three assists.

James impressed Heat coach Pat Riley.

"The only thing I can compare him to is 1979 when Magic Johnson came into the league and we were playing summer league games in front of 7,000 people," Riley said. "LeBron has the same kind of charisma, the same kind of talent, the same kind of maturity. His upside is just incredible."

James, who complained about a sore calf muscle after Tuesday's game, said the leg felt fine Wednesday. He played with it wrapped in a protective sleeve.