DOHA, Sept. 28 (Xinhua) -- The United States set the 4X400 meters mixed relay world record in the heat round at the 2019 IAAF Word Championships here on Saturday.

The US team, which consists of Tyrell Richard, Jessica Beard, Jasmine Blocker and Obi Igbokwe, clocked three minutes, 12.42 seconds to finish on top of the 16 teams in the heats. Their time became the new world record in the event, which was only included for the first time into the World Championships.

The previous best time of the event was 3:13.20, which was set three years ago in an American local event in Eugene.