Allyson Felix © Action Images

Allyson Felix and Sanya Richards anchored 4x100 and 4x400 relay triumphs for US women while Jeremy Wariner did the same for the US men in the 4x400, serving notice the Americans will again by a major force in relays at the Olympics.

"We're ready," Richards said. "We want to sweep the relays like we did at the worlds in 2007 and we're going to work really hard to do it this year."

But disaster struck the strongest US men's squad in the 4x100 relay.

Dixon was the leadoff man for USA Red in the men's 4x100-meter relay and was struck on the left side of his face by neighboring Canadian runner Charles Allen as each went to make his exchange.

USA Red also included US stars Tyson Gay, Wallace Spearmon and Doc Partton and recovered to finish fourth behind winner Jamaica but Dixon was taken from Franklin Field to be examined by doctors.

"Leroy got off to a great start," Spearmon said. "I went six steps and put my hand back. It looked like he got hit by something. He had a gash down his face. They had a towel on it. He was bleeding some." Dixon continued and made the handoff, later saying, "That was simply adrenaline."

"Hopefully the lanes (at Beijing) won't be so tight," Spearmon said.

"I had to slow down and readjust to get the stick and put it in position so Tyson could take it to the finish."

Jamaica, which did not feature 100-meter world record-holder Asafa Powell, won the 4x100 title in 39.04 seconds. Marvin Anderson, Michael Frater, Nesta Carter and Dwight Thomas edged USA Blue - John Capel, Xavier Carter, Michael Rodgers and Shawn Crawford - by one-tenths of a second with Trinidad and Tobago third in 39.33.

The US 4x400 women's relay of Richards, Felix, Natasha Hastings and Mary Wineburg won in 3:22.16, defeating Jamaica by 5.80 seconds with the best time in the world this year and a meet record, .77 under the US mark from 2005.

"Allyson ran great, Nat ran well and I was just able to open it up on the final leg," Richards said.

Wariner brought home LaShawn Merritt, Spearmon and Darold Williamson in 2:59.71 to win for USA Blue with the USA Red team of Xavier Carter, Bershawn Jackson, Kerron Clement and Angelo Taylor second in 3:01.12 and Jamaica third in 3:02.00.

"We ran a great race. We have a great team," Wariner said. "No telling what we will be able to do at the Olympics this year."

Felix anchored USA Red teammates Lauryn Williams, Miki Barber and Lisa Barber to victory in the women's 4x100 relay in 42.57 seconds with USA Blue - Muna Lee, Torri Edwards, Carmelita Jeter and Richards - second in 42.64 and Jamaica third in 43.31.

	Remember to go to www.supersport.com on your Mobile phone and keep in touch with the latest scores wherever you are.