SEATTLE, April 8 (Ticker) -- Desmond Mason scored a career-high 36 points, including the go-ahead jumper with 18 seconds left, as the Seattle SuperSonics clinched a playoff spot with a 102-100 victory over the Los Angeles Clippers.

The result also meant that Utah (42-35) joined Seattle (44-34) in the playoffs while the Clippers (38-40) were eliminated.

"I was trying to be cool," Sonics coach Nate McMillan said. "Of course, we felt the pressure, but as I told these guys, there's more pressure over there in that locker room than there should be in this locker room. They are in a do-or-die situation. We need to go out and play basketball the way we're capable of playing and whatever finish there is, we'll accept it."

NBA TV highlights from Clippers-Sonics: 56k | 300k Mason's big shot: 1,500k avi | QT Sonics coach Nate McMillan and assistant Bob Weiss celebrate good times and Seattle's return to the playoffs. Jeff Reinking NBAE/Getty Images

Los Angeles led, 95-90, after Jeff McInnis made a jumper with 3:34 remaining. But McInnis later missed 1-of-2 free throws and Quentin Richardson came up empty on a pair from the line with the Clippers ahead, 96-94, and 2:04 left.

After Vin Baker tied it with a jumper with 1:48 left, Michael Olowokandi made a hook shot to put Los Angeles back on top with 85 seconds remaining. But Predrag Drobnjak hit a jump shot and Mason snapped the 98-98 deadlock with his jumper over Darius Miles' outstretched arm from near the top of the key.

Richardson missed a bank shot with six seconds remaining, and the rebound went to Ansu Sesay, the NBDL Player of the Year who signed with Seattle for the rest of the season Monday. Sesay calmly iced the win with a pair of free throws with three seconds left.

"I just tried to relax and shoot them like I do in practice every day," Sesay said.

The game was tied at halftime, 49-49, before Mason scored 19 third-quarter points to stake Seattle to an 80-73 lead heading into the final period.

"I started feeling good," Mason said. "The basket looked huge. I mean, it was going down for me."

"He did everything tonight," teammate Brent Barry said of Mason, who made 16-of-22 shots. "He was shooting the ball well from the perimeter. He did a great job of driving in, he was rebounding well, and I think I saw him selling popcorn at halftime."

Gary Payton added 22 points and 13 assists for the Sonics, who snapped a three-game losing streak.

Elton Brand had 22 points and nine rebounds and Eric Piatkowski also scored 22 points for Los Angeles, which lost three of four meetings with Seattle this season.

"Some lucky bounces went their way, they got a few rebounds and they really stepped up and hit some big shots," Brand said. "They really played hard."

Although the Clippers shot 57 percent (40-of-70), they allowed the Sonics to connect at 58 percent (45-of-77).

"It was one of the better NBA games that we've been involved in this year," said Barry, who had 14 points on 6-of-8 shooting. "They shoot 57 percent, we shoot 58 percent, and there's some great hustle plays and big shots down the stretch in a close game. And you know the home team wins, so what more can you ask for?"

The Clippers, who made just 17-of-28 free throws, lost for the fourth time in five games.

"It's really disappointing," Piatkowski said. "We've got a lot of talent and we've come a long way. Our goal from the beginning of the season was to get to the playoffs. I certainly believe that next year we won't be trying to sneak into the playoffs, we'll be well into the playoffs.

"The mature teams are the teams that take care of business, and they win all the games that they are supposed to win. We've let a couple slip away and that's probably why we aren't getting in."

Seattle, however, returns to the playoffs after a one-year absence.

"We had to go about it a different way, but right now is a very exciting moment," McMillan said, "not only for me and the organization, but for the players and the fans because we've tried to do the things right this season and teaching these guys how to play the game -- play with respect, play together, work hard. And tonight everybody contributed, all of our guys."