CLEVELAND - The NBA playoffs won't go on without the defending champions. The Miami Heat didn't let a season of bumps, bruises or bad luck stop them from making a run at another title.

Miami Heat coach Pat Riley, right, instructs James Posey (42) during a timeout in the first quarter of an NBA basketball game against the Cleveland Cavaliers, Thursday, April 5, 2007, in Cleveland. (AP Photo/Mark Duncan)

Antoine Walker and Shaquille O'Neal scored 20 points apiece and the Heat clinched a spot in the Eastern Conference playoffs Thursday night, beating Cleveland 94-90 in overtime to drop the Cavaliers three places in the postseason seedings.

With Dwyane Wade watching from the bench in street clothes but nearing a return from his dislocated shoulder, the first-place Heat, who not long ago teetered on missing the playoffs because of injuries, moved 1 1/2 games ahead of Washington in the Southeast Division.

"Oh, good," Miami coach Pat Riley said upon hearing his team was in. "My worst nightmare was to win a championship, and then not make the playoffs the following year. We're in, but we're shooting for much higher things.

"I always thought despite the ups and downs that we would at least make the playoffs."

Done deal. The Heat have fought their way back from injuries to Wade, O'Neal (knee surgery), Jason Williams (knee and stomach problems), Jason Kapono (sprained ankle) — even losing Riley for 22 games because of surgeries to his knee and hip.

"We've been through so much adversity," Udonis Haslem said. "All the things that we went through, we stuck together. It's a tremendous accomplishment at this stage of the season to be able to clinch."

Walker made six 3-pointers and Alonzo Mourning had a big block in the final minute of overtime. Williams chipped in by stealing a pass by LeBron James with 27 seconds left and made three free throws in the last 24 for the Heat, who could have Wade back as early as next week.

Walker came off the bench and played 25 minutes as Miami's reserves outscored Cleveland's 36-7.

"I was trying to give us a spark," Walker said, "and tonight I did. I got a few open looks and got it going."

James, who didn't hide his frustration several times, scored 35 points with nine rebounds and five assists. Drew Gooden had 14 points and 14 rebounds for the Cavs, who fell from second place to fifth in the East.

If the playoffs started tomorrow, Miami and Cleveland would meet in the first round — not the matchup the Cavaliers would want. The Heat, though, would welcome playing anyone after what they went through.

Meanwhile, the Cavs, who are 4-6 since winning eight straight, are sputtering at the worst time possible.

"It's not over," Gooden said. "We can't look back and deal with woulda, shoulda and coulda. We never gave up, but the most disappointing thing is we had a chance to win it in overtime and we didn't."

The Cavaliers outscored the Heat 11-0 to force OT, but couldn't come up with a big play in the extra five minutes. Cleveland's spurt came after James stormed to the bench and kicked over an empty chair.

As they did in winning their first title a year ago, the Heat were clutch when it mattered most.

Kapono, the NBA's leading 3-point shooter and long-range champion at this year's All-Star Game, hit a 3-pointer with 1:23 left to give the Heat an 88-87 lead. On Cleveland's next possession, Zydrunas Ilgauskas was long with a jumper and his air ball bounced to Sasha Pavlovic.

With the shot clock winding down, Pavlovic tried a quick layup but had it blocked by Mourning.

Haslem's two free throws put Miami ahead 90-87. James then tried to drive the lane and kick a pass out for a 3-pointer to Donyell Marshall, but Williams alertly snatched it and was fouled.

He made one free throw to make it 91-87, but Marshall missed a 3-pointer and the Cavs had no choice but to foul. Mourning missed two attempts with 13.5 seconds left and James hit a 3 to get Cleveland within one.

Williams was then put on the line, and the 93-percent free-throw shooter, made both to put the Heat ahead 93-90. Larry Hughes then forced a cross-court inbounds pass intended for James that was picked off by Eddie Jones, who was fouled and made one foul shot to ice it.

Wade would like to return for the final regular-season games so he's ready for the playoffs, and he looked good while working out for more than 45 minutes under the watchful eyes of Heat assistant coaches and trainers.

Riley said a decision on the date of Wade's return could come as early as Monday.

"I do know that he is getting closer everyday, but it's his decision on when to come back," Riley said.

Notes:@ This will be the Heat's 12th trip to the playoffs and their fourth straight. ... James was sorry to hear about the season-ending injury suffered by Wizards G Gilbert Arenas. The two All-Stars matched big shots during a memorable playoff series last year. "It's definitely sad to see him go down on something where there's nothing you can do about it," he said. "Hopefully he does his rehab and gets back and comes back stronger. It's disappointing. I love competing against that guy and being a friend, I hope for the best." ... The Cavs went 17-for-17 in the fourth quarter from the line.