United States relay teams break records, Usain Bolt's Jamaica beaten

Two United States teams broke world records at the IAAF World Relays in the Bahamas, while Usain Bolt came out of the event a loser.

The niche event, which features only track relays, saw the US men's and women's teams break the world marks in their respective distance medley events.

On Saturday, the team of Treniere Moser (1200 metres), Sanya Richards-Ross (400m), Ajee Wilson (800m) and Shannon Rowbury (1600m) completed the women's medley in a time of 10 minutes, 36.50 seconds.

It beat the previous mark set by another US quartet earlier in 2015 of 10:42.57.

The men followed suit on Sunday, as Kyle Merber (1200m), Brycen Spratling (400m), Brandon Johnson (800m) and Ben Blankenship (1600m) narrowly set the world's best time of 9:15.50.

It beat the previous mark, set by a Kenyan team nine years back, by 0.06secs.

On Saturday, Bolt and his Jamaica team-mates were beaten by United States in the 4x100 metre relay at the IAAF World Relays in the Bahamas.

Justin Gatlin, Ryan Bailey, Tyson Gay and Mike Rodgers combined to post a time of 37.38 seconds on Sunday - edging the 37.68secs set by Bolt, Nickel Ashmeade, Nesta Carter and Kemar Bailey-Cole.

Nigeria won the women's 4x200m final in a time of one minute, 30.52 seconds, with a Jamaica team - featuring three-time Olympic gold medallist Veronica Campbell-Brown - second.

United States took the honours in the men's 4x800m final in a time of 7:04.84.

The Jamaica/USA duopoly continued on Sunday, as all six finals - including the Americans' second world record achievement of the meet - saw the two athletics powerhouses top the podium.

On Sunday, LaShawn Merritt and his US team-mates won the 4x400m final in 2:58.43.

In the women's 4x100m, Jamaica were led to victory by Campbell-Brown in a time of 42.14.

Ashmeade was involved as Jamaica clocked 1:20.97 to win the men's 4x200m.

Richards-Ross earned her second gold medal of the meet in the women's 4x400m, with the US registering a winning time of 3:19.39, while the Americans also reigned in the women's 4x800m final in 8:00.62.