After 300 stitches the doctors stopped counting.

Victim of an unprovoked attack, Kelli White's face was slashed so brutally that her friends could see her skull.

Now only a thin scar around her eye is a reminder of a horrendous assault for the woman who on Thursday should become the first American to win the world 100-200 double.

The gap left by the absence of triple Olympic champion Marion Jones, who gave birth to a son in June, has been filled more than adequately by the 26-year-old Californian.

White won the 100 metres on Sunday night and warmed up for her favourite event with an untroubled semi-final victory on Wednesday in 22.50 seconds.

The race was evidently harder than it looked to spectators in the Stade de France.

"I wish it was over, I'm tired," she said. "But that race today gave me a lot of confidence for tomorrow and we'll see what will happen."

No U.S. woman, including Jones, has ever won both events in the 20-year history of the world championships. Only three, again including Jones, have won the Olympic double.

The graceful, long-legged Wilma Rudolph, 20th in a family of 22, won both events at the 1960 Rome Olympics.

In 1988 Florence Griffith-Joyner, whose 100 and 200 world records set during a surreal summer still stand, emulated Rudolph in Seoul.

Twelve years later Jones was equally dominant, if not as swift, in Sydney.

Only two women, both East Germans, have clinched the world double. Silke Gladisch won in Rome in 1987 and Katrin Krabbe triumphed four years later, before running foul of the drugs testers.

White said she had not had a lot of sleep since Sunday's victory.

"My mum gave out the hotel number to my family so they've been calling kind of early. They forget the time difference," she said.

If she wins, as she should on Thursday, White can forget about sleep for the rest of the championships.