SEATTLE, April 17 (Ticker) -- The Seattle SuperSonics clinched seventh place in the Western Conference with an easy 109-94 victory over the Memphis Grizzlies as Desmond Mason scored 33 points and Gary Payton added 30.

The SuperSonics (45-37) came in having lost three straight games and six of seven to fall into a tie with Utah. Both teams were trying to avoid finishing eighth, which would mean a first-round playoff matchup with the top-seeded Sacramento Kings.

"We got a little too relaxed," Seattle center Jerome James said. "This is not the time to relax. This is the time to earn your money. It goes from being a game and fun to being a business. Those who have taken care of business in the season are now in the postseason." Utah held the tiebreaker over Seattle but lost at home to San Antonio. Seattle made sure it did not suffer a similar fate against Memphis, the last-place team in the Midwest Division

NBA TV highlights from Grizzlies-Sonics: 56k | 300k Gary Payton scored 18 of his 30 points in a third quarter that put Memphis away. Jeff Reinking NBAE/Getty Images

Mason, whose game has flourished over the last month, sparked a second-quarter run that gave Seattle the lead for good. The Sonics scored 73 points in the middle two quarters, turning the game into a rout and remaining perfect at home against the Grizzlies.

Seattle will open the postseason against second-seeded San Antonio. The Sonics split four games with the Spurs this season but has not won a playoff series since 1998.

"It's just nice to win a game," Sonics coach Nate McMillan said. "It's good for us that we played the way we did with the energy and intensity to have a good feeling about ourselves, to give us the confidence going into the playoff matchup with a very good San Antonio team."

"We've got to get prepared, get serious about our situation and go down there loose," Payton said. "We don't have nothing to lose, so we'll go in there, play hard and try to get us one (win) and we'll be fine."

Stromile Swift scored a career-high 31 points and grabbed 10 rebounds for the Grizzlies, who fell to 0-13 all-time in Seattle. Memphis (23-59) failed in a bid to set a franchise record for wins in a season.

Mason made 13-of-16 shots and 7-of-9 free throws. He fell three points shy of his career high, set April 8 against the Los Angeles Clippers.

"If I get my shots, I'll take them," Mason said. "My teammates find a way to get me the ball in the right position."

Playing just 33 minutes, Payton made 12-of-18 shots and handed out nine assists as he thoroughly outplayed Memphis point guard Jason Williams.

The Sonics trailed 29-26 after one quarter but took the lead for good at 30-29 on a jumper by Payton in the first minute of the second period. That was part of a 24-8 surge in which Mason scored eight points and rookie Predrag Drobnjak added six.

Mason's slam made it 50-37 with 4:56 left in the first half.

"He's been streaky. Some nights he's stroking the ball and making the right decisions and some nights he looks like a second-year player," McMillan said. "He's always aggressive in giving you 100 percent on the defensive end. When his offense is going, he's just that much more valuable."

The Sonics opened a 62-46 halftime lead and put away the Grizzlies with a 37-point third quarter.

"We had a lot of intensity," Payton said. "That's the way we should go into the playoffs."

James and Drobnjak scored 12 points each and Brent Barry added 10 and nine assists for Seattle, which shot 52.5 percent (42-of-80) and forced 23 turnovers, converting them into 29 points.

Shane Battier scored 14 points and fellow rookie Pau Gasol added 13 for the Grizzlies, who shot 50 percent (36-of-72).