DETROIT (AP) _ Nancy Kerrigan was going to prove emphatically that she had risen from the depths of a yearlong skating slump. Instead, she met unimagined adversity and must start all over again.

She has six weeks to do it.

Kerrigan, the 1993 U.S. Figure Skating Championship winner, withdrew from the event Friday, saying she was ''upset, hurt, angry'' that an unidentified attacker robbed her of a chance to defend her title. Kerrigan was smashed on the leg with a club or metal bar after practice Thursday and sustained a severely bruised knee and a bruised tendon.

Early Friday, after she unable to hop when doctors asked her to test the right leg, she was forced to withdraw.

''Right now, I'm going to focus on just getting better and hopefully get ready for the Olympics. I never worked so hard as I did this year,'' she said.

Trying to fill the void and make a comeback is Tonya Harding, the 1991 winner who has struggled on and off the ice over the last two years. She led after Friday's technical program. The competition ends Sunday.

Kerrigan, the 1992 Olympic bronze medalist, would have to be given a spot on the U.S. team for next month's games in Lillehammer, Norway. The U.S. Figure Skating Association is empowered to do so, and there is every indication it will. The United States has two berths in the Olympics.

''No spot is reserved for anyone until after the competition,'' said Claire Ferguson, president of the USFSA, who spoke to the women competitors and their coaches before the technical program Friday. ''I reminded them of the rules. They're veteran coaches and have been through this before.''

The USFSA went through this in 1992 with national champion Todd Eldredge, who withdrew from the U.S. championships with a back injury. He was placed on the Olympic team instead of Mark Mitchell, but was not in competitive shape for Albertville and finished 10th.

Kerrigan's peers didn't seem disturbed by the possibility she would be put on the team at the expense of one of them.

''I would accept it,'' said Nicole Bobek, who was second heading into today's free skate. ''Nancy's been in it much longer and if the (officials) think she deserves to go, that's their choice.''

At a news conference Friday, Kerrigan described the attack and her emotions concerning it.

''I was coming off the ice and went through curtains and was walking away from the ice when I heard something behind me,'' she said. ''I turned and saw somebody running behind me and he whacked me with a long black stick and it was really hard, and he kept running.''

The assailant escaped.

Evy Scotvold, Kerrigan's coach, criticized the lack of security in the area at Cobo Arena, which is adjacent to Joe Louis Arena, the site of the competition.

''When she went down, I ran looking for security,'' he said. ''We're not saying there was no security in the building, but there was none for 100 yards. I ran in both directions looking for them.''

Added Kerrigan, ''I was a little upset when I fell down and nobody was there. I had to scream, 'Somebody help me.' ''