Two free throws by Bob McAdoo with eight seconds left and another by Michael Cooper with two seconds to go beat Seattle and gave host Los Angeles the championship of the Pacific Division.
The Lakers hold a four-game lead over the Sonics. Each team has four games left, but Los Angeles has a 4-2 season-series edge over Seattle.
The Lakers led most of the way, but the Sonics battled back in the last period, Jack Sikma's jump shot with 40 seconds making it 104-all.
Then Kareem Abdul-Jabbar committed an offensive foul, but Gus Williams missed two jump shots and Sikma was called for a loose ball foul on McAdoo during a battle for a rebound underneath the Seattle basket. McAdoo made his free throws, Seattle called time, then Lonnie Shelton made a bad inbounds pass and Sikma fouled Cooper.
Among those in the crowd watching was Virginia center Ralph Sampson, in town to accept the John Wooden Award as the L.A. Athletic Club's player of the year. A Lakers spokesman said team owner Jerry Buss has offered San Diego, last in the West Division, draft choices and cash for its pick in the draft should Sampson decide to make himself eligible, but that the Clippers have not accepted the offer. The Lakers already own the pick of Cleveland, last in the East.