Allyson Felix knows the code of the Penn Relays, which means she doesn't want to hear the "whoop, whoop, whoop" from the Jamaican fans in the stands at Franklin Field informing her that someone is closing in on her.

Felix had no such problems yesterday. The 21-year-old wunderkind blistered the track both times she received the baton in leading her USA Red team to victory in the 4x100 and 4x400 relays in the USA vs. the World competition before a crowd of 46,363.

Teams from the United States won five of the six races in the annual event on another cool and mostly cloudy day, failing only in the men's distance medley relay to an all-star squad from different countries.

Felix, though, was the only runner to be part of two winning teams, running the second leg and looking swift and smooth both times. In fact, her unofficial time of 50.0 seconds on her 4x400 split broke the race open and enabled teammates Moushaumi Robinson and Debbie Dunn to coast home in 3 minutes, 24.70 seconds and soak in the cheers.

"I haven't run that many 4x4s, so I was happy to come here and get some experience with the girls and just run a good leg," Felix said. "Running the 4x1 was a good warm-up for this. I didn't have to do too much to get ready. I was already pretty warm."

Mary Wineberg ran the leadoff leg on the 4x400. Felix competed on the 4x100 team with Lisa Barber, Muna Lee and Lauryn Williams. They finished in 42.87.

"Sometimes you can't tell where you are [on the track], and you don't know if you're going to get the 'whoop, whoop' or what," Felix said. "So I wasn't sure. I just wanted to come home strong, and it was a lot of fun to run here."

Felix hit the world stage immediately after her graduation from Los Angeles Baptist High School in 2003. She won Olympic silver in the 200 meters at the 2004 Athens Games and took the 2005 world outdoor title at the same distance.

Felix now is pointing to this year's World Championships in Osaka, Japan, and the 2008 Olympics in Beijing. Since she excels at 100, 200 and 400 meters, it is still up in the air as to what events she will enter in the trials for the two international meets.

"I felt my conditioning is going really well," she said. "I've been able to handle some of the workouts better, and I'm feeling stronger than I have in years before. It's setting me up good, I think."

She said her coach, Bobby Kersey, wants her to go after the 400 so she would be available if needed on the 4x400 team at the worlds or the Olympics.

The women completed a U.S. sweep with USA Red's victory in the sprint medley, a win that became anticlimactic after Jamaica dropped the baton on the first exchange, silencing its fans. Hazel Clark anchored the winners in 2:01.5 for her 800-meter split.

The men of USA Red captured both the 4x100 in 38.35 and the 4x400 in 2:59.18. Shawn Crawford, the 200-meter gold medalist in Athens, anchored the sprint team and Darold Williamson, who won a gold as a member of the winning U.S. Olympic 4x400 team, brought his squad home.

A candid Crawford said later that he would have preferred to stay home and train rather than travel to Penn. He said he ran here only because of his contractual obligation to Nike, his sponsor.

"They're probably going to kill me for saying that," Crawford said. "But it's honest, and I try to be honest with everybody. . . . Coming here is getting a race in. But I remember back in the day when it was hard for me to even get into a meet and run, so I'm thankful for it, but it's really not all that important to me."

The only U.S. stumble came in the men's distance medley when Bernard Kiptum of Kenya kicked past USA Blue anchor Chris Lukezic in the final 80 meters to bring the World All-Stars home in 9:29.44.

The race featured a battle between two former Penn stars in the 800-meter leg - Sam Burley of Team USA and Courtney Jaworski of the World All-Stars.

"It was great to be back and great to run against Courtney," Burley said. "I always love running the relays."