In what were perhaps the most difficult bouts of their professional boxing careers, 1984 Olympic gold medalists Tyrell Biggs and Mark Breland remained unbeaten today in the obscure setting of the Americana Host Farm Resort.

Breland, 22, a welterweight, won a 10-round unanimous decision over previously unbeaten Troy Wortham. Breland knocked down Wortham in the sixth and ninth rounds to improve his record to 9-0.

Earlier, Biggs waited out a power shortage in the first round and went on to win an eight-round unanimous decision over heavyweight opponent James (Quick) Tillis (31-8). Biggs (8-0, six knockouts) is scheduled to fight next against David Bey on March 8.

Breland's manager, Shelly Finkel, said his fighter will have a bout in March against an undetermined opponent and in April against Darryl Anthony, who defeated him in the national amateur championships in 1981, the only setback of Breland's career.

Asked when he was planning to fight a top-10 contender, Breland said, "I'm not going to push myself. You all want to rush me for some reason, and I don't know why. I just want to be established."

Breland said his opponent today was more than he could handle. In addition, this was Breland's first 10-round bout.

"I knew he was going to come out aggressive," Breland said, "because he's been in 10-12 rounds before. In the gym, I was working a lot to the body. I thought I could try to move in and establish body shots in the first round."

"I think that was when the fight was established," said Wortham. "He came out and threw some good body shots. I came out stiff. He forced me to change my game plan. It wasn't one of my better fights."

In the sixth round, Wortham's knees wobbled when Breland connected with a right cross. Breland followed with a short left hook to drop Wortham near the end of the round. Breland's overhand left in the ninth round had Wortham hanging between the ropes.

The three judges favored Breland by margins of 50-38, 50-38 and 50-39.

Biggs' fight had a lot more to offer for the fans, especially when the lights went out before a national television audience with 1:09 left in the first round because a car ran into a power line. Tillis already had connected with two sweeping lefts and a left jab before the six-minute delay.

"I kind of predicted the lights would go out, but that was Tillis' lights," Biggs said.

Biggs was deliberate again in the second round, and Tillis, who has fought five world champions, was able to slip in a good left hook and some combinations. After Tillis used a left hook that appeared to hit below the belt, Biggs chased him to the ropes.

In the third round, Biggs put Tillis back against the ropes, connecting with a hard right cross and a left hook, leaving Tillis in a daze. But Tillis, his eyes rolling, fought his way out and both fighters tired. Biggs gave Tillis a wide smile as the round ended.

Biggs used the jab to score in the fourth round, but Tillis gained points in the fifth with three consecutive right crosses to Biggs' face.

The crowd wanted a knockout from Biggs in the sixth round, but when he had Tillis against the ropes, all he could get in were soft combinations. Biggs won the next two rounds, dominating the seventh, leading with the left and connecting with the right.

"He was a much better fighter than I expected," Biggs said. "He won the early rounds and I knew I had some catching up to do. In my preparation, I was told he would come out strong.

"The last couple of bouts, I was able to throw the hard punch," said Biggs, who knocked out Tony Anthony in the first round of his previous fight on Dec. 21. "But I've proved if that doesn't work, I can box. I'm kind of glad I didn't knock him out. It was a good experience."

Said Tillis, who fought Mike Weaver for the World Boxing Association title in 1981: "He is a good young fighter and strong. He had a good jab. He's going to mature a lot. He'll get even stronger as time goes on."

Biggs won on the three judges' score cards by margins of 39-33, 39-33 and 39-34.