The Seattle SuperSonics took a 2-0 lead over the Phoenix Suns in the NBA Western Conference finals tonight.

The Sonics won, 103-97, with guard Gus Williams scoring six crucial points in the final period. His first of four free throws put the Sonics ahead, 89-88, and they led the rest of the way.

Williams' fast-break layup and final two free throws provided the clinching points. He finished with 16 points.

Game three of the best-of-seven series will be played Sunday in Phoenix.

The first half was a series of streaks and Phoenix led 49-47.

Seattle, the Pacific Division champion, shot in front 12-4, but the lead didn't last long because of Phoenix guard Paul Westphal.

Westphal, the Suns' leading scorer during the regular season (24 points a game), made seven straight points and the Suns took a 19-14 margin.

The Suns, who finished second in the Pacific Division, expanded their margin to 32-23 because of an aggressive defense and Seattle's shooting troubles. Seattle hit only seven of 26 shots in the opening quarter.

Then guard Fred Brown and forward John Johnson pushed the Sonics back into the lead with 4:10 to play in the half.

After the Suns again staged a rally for a 47-41 lead, Seattle pared the margin on two free throws by forward Paul Silas, two more by forward Lonnie Shelton and a fast-break layup by center Jack Sikma as the half ended.

Westphal led all scorers in the half with 17 points. He made eight of 17 shots, most of them from the perimeter of Seattle's defense.

Seattle led after three quarters, 77-75. It controlled the rebounds, 18-7, and got strong performances from Johnson and Shelton.