BERLIN: For the last time, Usain Bolt will repeat that rhetorical question he has answered over and over again at this year's world championships — "Who's faster?"

As if anyone still questions what has been written on billboards and T-shirts across Berlin for weeks.

But on Saturday, he will need a little help from his Jamaican friends.

The great Jamaica-U.S. battle for sprint domination comes to a close with the 400-meter relay finals, and with the Caribbean island leading 3-1.

American sprinter Allyson Felix is responsible for keeping the fight from turning into another Olympian rout. Late Friday, she won her third straight 200-meter title, beating Olympic champion Veronica Campbell-Brown.

Last year, the Jamaicans won the runners' duel in Beijing 5-0.

Another gold for Felix in the women's 400 relay Saturday could still make it as close as possible. But then again, the U.S. men's team again botched a baton exchange and was disqualified for the second time in as many years. It effectively hands victory to the Jamaicans.

Two years ago, Tyson Gay won three golds in the sprints to lead the United States to an overpowering performance in Osaka, Japan, at the last worlds.

Now Bolt is poised to do the same.

And he sure won't waste the 23rd birthday present he got from his teammates when they qualified him for the final. Bolt sat out the heats, happy to give autographs to fans.

On top of that, Bolt received a second gold medal on the stands and accepted a second check of $100,000 for a world record, bringing his total to $320,000 in one week of work. There still is $180,000 at stake if the relay team sets another world record on the way to a third title.

Then again, that total would have to be shared with his teammates.

In the end, Felix might be going for three golds, too. After winning the 200, she will run the 400 relay and might just add a gold in the 1,600 relay on Sunday.

She left Osaka with the same three golds two years ago.

Triples could not be produced by people more different in style than Bolt and Felix, one hyperbole, brash and over the top, the other understated, composed, even withdrawn.

Instead of antics, posing and talk, Felix hardly raised one slender fist and little more than a smile at the finish when she broke the Jamaican hold on sprinting going back to last summer's Olympics.

She held off an early charge from Campbell-Brown, and once she entered the straight where her stride is at its most efficient, there was no stopping her.

"I was very confident about my strength," Felix said. "I defended my title. I cannot ask for more."

Overall, the United States jumped over Jamaica in the medals table with six golds and 16 overall. Jamaica is second with five gold and 10 overall.

The victory of Yaroslav Rybakov in the men's high jump and Sergey Kirdyapkin in the 50-kilometer walk gave Russia four golds and 11 medals overall.

Other finals Saturday include the men's long jump and pole vault, and the women's hammer, marathon and 5,000.