Updated

The finals for the men's 4x400-meter relay and women's 4x100 relay at the 2012 Olympics both take place on Friday, and the speculation about who, exactly, will be selected for the teams from nations' "relay pools" is now over. Team USA announced its lineups for the men's 4x400 final and the qualifying rounds of the women's 4x400 on Friday.

The U.S. men have been dominant in the 4x400 for many years, winning every gold medal in the event since 1984, though their gold in 2000 was vacated retroactively. The 2012 foursome of Bryshon Nellum, Joshua Mance, Tony McQuay and Angelo Taylor only has one holdover from 2008 (Taylor), but is still a favorite to claim gold again, after tying the Bahamas for the fastest time in qualifying.

Team USA has been similarly competitive in the women's 4x100 from 1984 to 1996, winning four straight golds, but the Americans haven't topped the podium since Atlanta and haven't medaled since Sydney, where they took bronze. Tianna Madison, Allyson Felix, Bianca Knight, and Carmelita Jeter give the U.S. a formidable quarter for Friday's final.

The final is also a long-awaited revival of the rivalry between Jamaica and the U.S. on the Olympic stage, and a chance for redemption for both squads, as handoff issues kept both from medaling in Beijing.

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