The usually timid Phoenix Suns outslugged the bigger and stronger Seattle SuperSonics today and got back into the Western Conference championship series with a 113-103 victory.

The Suns are still down two games to one, but they at least know they can beat the Sonics, and beat them with a 6-foot-7 rookie center.

The Suns' regular center and leading rebounder, Alvan Adams, sprained his ankle in the first period, but Joel Kramer came in and played superby to give the Suns the lift they needed.

Adams was hurt when he came down on a Sonic player with a minute left in the first quarter. He was helped to the dressing room and did not return to the game.

"Alvan is doubtful for Tuesday," said John MacLeeod, the Suns' coach. "Hopefully he'll be able to play Friday, though."

The fourth game of the best-of-seven series will be played here at Veterans Memorial Coliseum Tuesday night.

Kramer, from San Diego State, scored 11 points, grabbed six rebounds, blocked two shots, had three assists, three steals and took Jack Sikma, the 6-11 Seattle center, out of his normal game.

Even without Adams, the Suns were able to hold their own rebounding with the Sonics and that enabled them to get their fast break going for the first time in this series. In the first two games Seattle banged up the smaller Suns under the basket. Not today.

Seattle got six more rebounds than

Phoenix, but the Suns beat them on the offensive boards, 24-19.

"I think we screened out pretty well today," said Phoenix forward Truck Robinson. "We played a little harder, too."

Robinson scored 21 points and had eight rebounds and completely outplayed Sonic star Lonnie Shelton.

Paul Westphal led the Suns with 25 points and Walter Davis added 22, but more importantly, it was the Suns' defense that kept them in the game. The Suns forced 31 Seattle turnovers with their switching, double-teaming defnse and they forced Seattle out of its normally patient game.

"We played poorly as a team," said Seattle Coach Lenny Wilkens. "We were too much in a hurry and didn't take the time to read what was going on. They did a better job on the boards against us because we allowed them to. We just didn't play well.

"We were confident coming into the game, maybe too confident. You can be sure the next game will be different."

The Suns outscored the Sonics, 16-2, at the end of the third period and the beginning of the fourth to turn a 78-75 lead into a 94-77 advantage with 8:40 to play.

In part spurt, Westphal and fellow guard Mike Bratz had six points, the Sonics had six turnovers and committed six fouls.

Seattle never again got closer than 10 points.

Gus Williams led the Sonics with 35 points, but he had 24 of them in the first half and all 11 of his second-half points came after Phoenix had moved to its 94-77 lead.

"We played hard today, but I don't think we played particularly well," MacLeod said. "We were able to control the defensive boards when we took control of the game there in the fourth period and we got them out of their pattern.

"This was also the first time in the series we were able to establish a running game."

The Suns could be in trouble the rest of the series if Adams cannot play. Kramer played well, but he doesn't have the size or experience to carry the Suns.Behind him is seldom used and mostly ineffective Bayard Forest. Robinson played some center late in today's game.

"Injuries are part of the game," said MacLeod. "Joel played a fine game today and he has played well all year long. He has great instincts for the ball. He's extremely intelligent and a good passer."

As soon as he replaced Adams, with the Suns down, 30-27, Kramer asserted himself, getting two straight rebounds and forcing the Sonics into two loose-ball fouls buy getting good position under the basker. First Sikma climbed over Kramer's back and Kramer made one of two free throws to get the Suns to within two points. Dennis Awtrey then was called for pushing Kramer and the rookie again made one of two free throws.

Early in the second period he scored five straight points to bring his team from one down to a 40-36 lead.

"I just played like I normally do," Kramer said. "The only thing that changed about my game was that I knew Alvan wasn't coming back.