With an eye toward the 2012 London Games, eight athletes who have won Olympic gold medals are among the runners entered for the 13th edition of the USA vs. the World events at the Penn Relays, USA Track & Field announced Tuesday.

Five gold medalists scheduled to run - Lashawn Merritt, Angelo Taylor, Justin Gatlin, Sanya Richards-Ross, and Allyson Felix - will represent the United States, while three - Nesta Carter, Shelly-Ann Fraser-Pryce, and Sherrone Simpson - will compete for Jamaica.

The men and women will run in both the 4x100- and 4x400-meter relays Saturday. There also will be a men's distance medley relay and a women's sprint medley. A record total of 21 countries are expected to compete.

Other stars running for the United States include Walter Dix, who has clocked 9.85 seconds (wind-aided) in the 100 this year; sprinter Carmelita Jeter, the 2011 Jesse Owens female athlete of the year, and veteran distance runner Bernard Lagat.

Taylor (Georgia Tech), Gatlin (Tennessee), Richards-Ross (Texas), and Dix (Florida State) competed at the carnival as collegians, as did Phoebe Wright (Tennessee), Kerron Stewart (Auburn), and Bianca Knight (Texas).

Roethel, Dewart lead multi-events. With more than half the contestants who entered the decathlon and heptathlon having withdrawn, the two competitions did not attract enough competitors Tuesday to field a baseball team.

With a three-man field, of eight entered, in the decathlon, junior Richard Roethel of Christopher Newport (Va.) led with 3,691 points. Senior Emma Dewart of Ithaca (N.Y.), one of the five who remained from the original field of nine, topped the competition with 3,055 points.

Neither one seemed too disturbed by the small field.

"I kind of like it when it's like a practice environment," Roethel said. "There's not a lot of people here."

Dewart, a senior from Barker, N.Y., said she thought the field was just right.

"When there's a lot of people here, it becomes a little bit intimidating," she said. "But right now it's fine."

Roethel, who held a 76-point lead over Penn State's Anya Uzoh, said he was disappointed in his high jump of 6 feet, 6 inches, which was five inches off his season best. He had the best marks in the 100 meters (11.19 seconds) and the shot put (41-7).

Dewart got off to a great start, picking up 907 points with a 14.51-second clocking in the 100-meter hurdles. She also had the best time in the 200 (25.95) and high-jumped 5-61/2, tying her for first.

Dave Johnson, director of the Penn Relays, said participation has dipped for the multi-event competitions in recent years because Division I conferences include the decathlon and heptathlon at their championship meets, which usually fall one or two weeks after the carnival.

Johnson also thought the forecast for cool and blustery conditions Tuesday might have contributed to more withdrawals than usual.

He said he was looking at ways to bulk up the competition, maybe by having two conferences hold their decathlon and heptathlon competitions at the Penn Relays, or attracting greater numbers of Division II and Division III athletes.

"I'm convinced there are solutions," Johnson said. "It's just figuring out what the better solutions are."

Get complete 2012 Penn Relays coverage in Philly.com Sports' special section.