She broke her own 400m hurdles World Record(WR) with a 52.16s run!!! USA's Dalilah Muhammad had just set a new WR in July this year and at the Khalifa stadium in Doha she bettered that timing by 0.04s. Two World Records(WRs) in two days for the United States mixed relay team!!! The 4*400m mixed relay event made its World Championships …