The Philadelphia 76ers, who believed they had a strong shot to unseat the Detroit Pistons as Eastern Conference champions this season, learned yesterday that point guard Johnny Dawkins is gone for the season after suffering a torn anterior cruciate ligament in his knee Thursday night.

In Milwaukee, Dawkins's right leg gave way early in the first quarter. The injury was diagnosed on the spot as a tear in the ligament, near the knee joint, and Dawkins flew to Durham, N.C., to get the final word: a discernible tear.

"From what they saw, they feel that he is pretty much finished for the year," trainer Tony Harris said.

The extent of the injury won't be known until Dawkins has surgery. He likely will need six to 12 months of rehabilitation.

"We have to hope for the best," 76ers owner Harold Katz said, "but we have to prepare for not having Johnny this season."

Katz said the front office is working to land a guard who would be "more than a stopgap."

"We've been through all the names. I don't think there's a name we missed, even in Europe," Katz said of a long afternoon spent sequestered with General Manager Gene Shue. "We'll try to do the best with the situation without giving up on the season. I hope we can get something done this weekend."

Said Shue: "That was a real tough blow to the club, to lose a player like Johnny, who was off to an incredible start."

The 76ers, somewhat short-handed at guard before the injury, are in a dire situation now. Only three guards -- Hersey Hawkins, Rickey Green and rookie Brian Oliver -- are on the roster, meaning forward Ron Anderson probably will move to the backcourt.

Coach Jim Lynam, while not underplaying the importance of Dawkins, said he has confidence in the players still around.

"We've got two guys in Rickey Green and Brian Oliver, both of whom can play the point," Lynam said. "I make no apology for either of them. What it's all about is guys stepping up when called upon. If we've got a chance to grab someone that will help us, fine. But we just have to assess where we are and go from there."

Trail Blazers: Portland and Jerome Kersey finalized an $11 million, four-year contract extension, through 1995-96, the forward said.

Kersey, 6 feet 7 and in his seventh season, averaged 16 points per game last year as the Trail Blazers won the Western Conference title.