At least that's what Leroy Dixon found out.

Dixon, leading off for the U.S. Red team in the men's 4x100 relay, was about to make his baton exchange with Wallace Spearmon when he was struck in the left eye by an inadvertent flying fist from Canadian runner Anson Henry in the lane to his left, pretty much knocking his unit out of the race. Dixon suffered a scratched pupil and met reporters with a patch over his eye.

"That was a new one on me," Spearmon said. "I thought we were racing Mike Tyson."

However, after winning just one of the first four events on an overcast, breezy day, U.S. runners made it a .500 day by winning both 4x400 relays, with the women's side doing it in carnival record time.

The U.S. Blue team of Mary Wineberg, Allyson Felix, Natasha Hastings and Sanya Richards blistered its four laps in 3 minutes, 22.16 seconds, topping the old mark by 0.77 seconds. The U.S. Blue men's team, anchored by Olympic gold medalist Jeremy Wariner, followed by breaking the tape first in 2:59.71.

Felix, winner of three gold medals at last year's World Championships, duplicated her feat of last year at the carnival by participating on two winning teams. She also anchored the U.S. Red team to victory in the 4x100 in 42.57 seconds, behind Lauryn Williams, Miki Barber and Lisa Barber.

"I was pleased with the way I ran," the 22-year-old Felix said. "It was good to come out and get familiar with the girls. I thought the 4x1 went well. I came back, and it was a privilege to run with these [4x400] ladies. We ran well."

The day was one of mixed results for Tyson Gay, the U.S. Olympic gold medal hopeful at 100 and 200 meters this summer in Beijing, and Wariner, who won the 400 meters at the last Olympics (2004) and the last two World Championships (2005, 2007).

Gay never got a chance to draw attention to his ability because of the accident involving teammate Dixon in the 4x100, although he ate up ground rather quickly on his anchor leg and brought the U.S. Red team in fourth in 39.38, which compared with Jamaica's winning time of 39.04.

"They had a huge lead and I couldn't catch him, but that's how it goes," Gay said. "That's my first time running the anchor leg here, and I wasn't used to the stagger. It seems like I ran 50 meters and the race was over."

Wariner, the 2004 Olympic champion at 400, ran easily thanks to the lead given him by teammates LaShawn Merritt, Spearmon and Darold Williamson. He was clocked at 44.9 seconds for his 400 leg and looked forward to breaking Michael Johnson's long-standing record of 43.18 in the 400 later this year.

"That's one of my main goals besides defending my title in the Olympics," said Wariner, who was making his Penn Relays debut. "I want to break his record and be the first to run 42 seconds. I'm working hard every day at practice just to get to that point. I know every part of my race has to be perfect to do that."

Gay, who had a U.S.-best time of 9.84 in the 100 last year, said he planned on entering the Olympic trials in the 100 and 200, plus the 4x100 relay. He said he also would love to run on the 4x400 relay but acknowledged the strength of his nation's 400-meter runners.

"If they wanted me to run [on the 4x400], I would," he said. "But we're so strong in the 4x400 it might not be a possibility."

Other "USA vs. the World" winners yesterday were Jamaica in the women's sprint medley (3:37.61) and Kenya in the men's distance medley (9:29.79).