The 18-year-old McLaughlin clocked 50.97sec during the preliminary rounds on Saturday before cocking the World U20 record of 20.52 to break 14-year-old Sanya Richard-Ross' World Junior record in the final.
SEC Indoor Championships 2018 Women's 400m Final Results:
1. Sydney MCLAUGHLIN FR Kentucky 50.52 PB MR
2. Lynna IRBY FR Georgia 50.62 PB
3. Sharrika BARNETT JR Florida 51.81
4. Morgan BURKS MAGEE FR Arkansas 52.42 PB
5. Rachel MISHER JR LSU 53.23
6 .Taylor MANSON FR Florida 53.48
7. Jennifer EDOBI SR Vanderbilt 53.88 SB
8. Lenysse DYER JR Tennessee 53.89