Herschel Walker, star tailback at the University of Georgia, broke his right thumb during scrimmage at Sanford Stadium yesterday and will miss at least two games.

Coach Vince Dooley said team doctors will operate on the thumb this morning and that Walker probably will wear a cast three to six weeks.

Dooley said Walker will miss at least the opener against Clemson Sept. 6 and the game against Brigham Young Sept. 11.

"I don't think I need to elaborate on the loss to the team," Dooley said. "It's just part of football. Someone else will just have to step forward at that position." He said Carnie Norris, Tron Jackson and Keith Montgomery are possibilities.

Walker scored 35 touchdowns in his first two years at Georgia. He gained more yards (1,616) than any other freshman ever, then he gained more than any other sophomore ever (1,891). He had been overwhelmingly favored to win the Heisman Trophy this year, and the injury won't help his chances.

In 1980, Walker was third in the voting behind seniors George Rogers of South Carolina and Hugh Green of Pitt. Many felt Walker should have won because he outperformed Rogers when Georgia played South Carolina.

Walker was favored to win last year but senior Marcus Allen of USC set the NCAA rushing record and won . . .

The Detroit Lions have fired Billy Sims, or so Sims' lawyer contends. The Lions had written the lawyer to assert that the player union's moratorium on individual negotiations keeps them from bargaining now. "The way I read it, he's being fired," the lawyer said . . .

Locally, quarterback Sandy Nichols threw a 50-yard pass to end Perky Warner for the only touchdown as Howard University held its first full-contact scrimmage this season. Coach Floyd Keith liked what he saw . . . So did Bobby Ross at Maryland, who is holding two-a-day drills . . . Gary Tranquill of Navy wasn't so happy. "We weren't very impressive today," he said. "We lacked enthusiasm and appeared to be sluggish. It could have been from the two-a-days we've been doing all week." Next Saturday, the team will have a refereed scrimmage that will be open to the public.

Basketball: Quintin Dailey, the Chicago Bulls' first-round draft pick, scored 30 points at Civic Center to help lift the Baltimore All-Stars over the Washington All-Stars, 148-143. Playing before a home-town audience, Dailey said jubilantly: "This is my home; there's nothing like home . . . nothing like it." Also playing for Balitmore were former University of Maryland players Ernest Graham (30 points) and JoJo Hunter (28).