Philadelphia: Showdowns between US and Jamaican sprint stars will spark the 12th edition of USA versus the World events at Saturday`s 117th Penn Relays.
Men and women will compete in 4x100m and 4x400m relays with women also in a sprint medley relay and men contesting a distance medley relay.
More than 180 athletes from 16 nations also will compete including lineups from Australia, Canada, Kenya, Morocco, Brazil and Britain.
While Usain Bolt will not be on hand to try and beat his 8.79-second anchor leg from 2010, Jamaica will have 100m stars Asafa Powell, Michael Frater, Nesta Carter and Steve Mullings, who owns the season`s best time in 9.90 seconds.
They face an American lineup that includes five of last year`s top 10 at the distance, including 2011 US pace-setters Ivory Williams and Mike Rodgers, reigning US 100m champion Walter Dix and 200m champion Wallace Spearmon plus Darvis Patton and Shawn Crawford.
Two-time world champion and Olympic runner-up Kerron Clement, two-time US runner-up Johnny Dutch, Kansas Relays winner Bershawn Jackson and fellow hurdles veteran Angelo Taylor lead a US bid for an 11th 400m title in 12 tries.
Kenya and the World All-Stars have won every distance medley relay since the event began in 2006 and the American bid to end the drought will be tested by Australia, Kenya, Canada and first-time meet competitor Ethiopia.
Bernard Lagat, a nine-time world or Olympic medalist, will compete in the USA-world showdown for the first time since 2006 when he helped set an American record.
US 800m star Nick Symmonds, 2010 anchorman Leo Manzano and 2011 world 1,500m leader Russell Brown are also in the US relay pool.
US women have a six-year 100m win streak with Allyson Felix having run on the past four US winning lineups and Carmelita Jeter, this year`s world leader in 10.99, having run on the past two winning relays.
Lauryn Williams, Bianca Knight and Marshavet Meyers are also in the pool and own this year`s world-best relay time on 42.45 from the Texas Relays. Also in the pool is 2008 US champion Muna Lee.
Jamaica will feature reigning Olympic and world Champion Shelly-Ann Fraser and Olympic medalists Kerron Stewart and Sherone Simpson. Germany, Bahamas, Brazil and the Caribbean All-Stars quartet will also test the US domination.
US women seek an 11th 400m win in 12 tries, with Sanya Richards-Ross and Felix each bidding for a fifth title. Richards-Ross is coming back after an injury-riddled 2010 season.
Jamaica offers a huge challenge with reigning Olympic and world 400m hurdle champion Melaine Walker joined by fellow hurdler Kaliese Spencer.
The women`s sprint medley relay has gone to Jamaica the past three years and veteran 800m anchor-leg runner Kenia Sinclair will be back in search of a fourth consecutive triumph.
The Americans, Russian Nigeria and Canada will offer challenges.