Gus Williams' 16-foot jump shot with 52 seconds remaining provided the winning basket today as the Seattle SuperSonics nipped the Phoenix Suns, 106-105, to force a seventh game in their National Basketball Association Western Conference final playoff series.

The victory evened the best-of-seven series at 3-3, and the Sonics can return to the NBA final for the second straight year by winning Thursday at the Kingdome.

"The seventh game is history," said Sonic Paul Silas. "If we take it to them like we did today, there's no way they can win."

The Sonics, who appeared demoralized Friday after losing their third straight to the Suns, pulled themselves together today and took charge at all the crucial times.

"We had started second-guessing ourselves," said Seattle Coach Lenny Wilkens, "but we just relaxed and gave it our best effort."

"This team hasn't quit all year and we weren't going to quit now," added Silas. "We didn't do anything different. We just played harder. We played like we wanted to win the ball game."

The Sonics pounded the boards relentlessly, outrebounding the Suns, 43-27, and they made up a five-point deficit in the final 4 minutes 22 seconds.

A Walter Davis drive down the middle gave the Suns a 101-96 lead. But Jack Sikma, who came out of his series-long slump today with 21 points and 10 rebounds, scored four straight Seattle points to get the Sonics to within one, 101-100, with 3:30 to play.

Paul Westphal got the Phoenix lead back to three with an 18-footer 20 seconds later.

On Seattle's next possession, Lonnie Shelton grabbed a missed Sikma shot and muscled it in to once again get the Sonics to within a point. Then, with 1:33 left, Westphal made two free throws after Sikma fouled him for a 105-102 Phoenix lead.

Williams was fouled by Gar Heard as he drove to the basket with 1:22 left and he converted two free throws. At the other end of the floor, Davis tried to force a pass inside to Truck Robinson and it sailed out of bounds for a turnover,giving the ball to Seattle with 1:07 left and the Sonics down, 105-104.

Williams took an awkward 18-footer and missed, but Shelton outbattled Robinson and Heard for the rebound and threw the ball back out to Williams.

Williams got nothing but net this time.

"As soon as I got the rebound I knew we had time and there we no need to hurry," said Shelton. "They (the Suns) were all over me, so I just passed it outside."

"I had to take that shot," Williams said. "That's in my range."

Phoenix still had a change to win it, but when 41 seconds left, Davis was called for traveling as he tried to maneuver around Shelton at the top of the key.

Williams missed at the other end for Seattle and Sikma missed a tap-in attempt with Heard rebounding for Phoenix with 16 seconds left.

The Suns called a timeout, but Davis took a 20-footer under pressure that missed badly with four seconds left. The Sonics fumbled the rebound out of bounds with a second left.

Phoenix in-bounded the ball to Heard, but his 17-footer at the buzzer was not close.

"Our bench was productive today it hadn't been in the last three or four games," said Wilkens, "but the big thing was that we were patient and we kept coming back whenever we got down. We're a good ball club and we know it. We didn't win 52 games this yearon a fluke. When we play our game we can beat anybody anytime. Today we played our game."

It helped the Sonics immeasurably that Sikma, who was shooting 14-56 the last four games, found his offensive game. He made sevn of 11 from the field and caused the Suns all sorts of problems inside.

Fred Brown also got hot as he made seven of 11 shots, scoring 15 points in 16 minutes.

Dennis Johnson led the Sonics with 23 points and carried them offensively much of the game.

But it was Silas who set the tone for the Sonics. He scored 10 points and grabbed nine rebounds, eight offensive, and played like a man hungry for a championship ring.

"I just felt that I wasn't going to let us lose," the 35-year-old Silas said. "We needed somehing to get us motivated and it was a case of each man doing whatever he could."

Joel Kramer, playing for injured center Alvan Adams, scored a career high 19 points for Phoenix. Westphal led the Suns with 29 and Davis had 26, but without the rebounding the Suns faded.

"The key is the offensive rebounding," said Phoenix Coach John MacLeod. "You just can't consistently give them up and except to stay in the game."

Phoenix got 12 offensive rebounds which it turned into nine points, but Seattle had 18, good for 19 points.

The Sonics' pounding also showed in the Suns' fourth-quarter shooting. They were shooting 59 percent going into the final period, but made only five of 18 in the last 12 minutes.