Jabari Matheson (left) wins his first round heat in the men's 400m on Thursday's second day of the World Under 20 Championships at Hayward Field in Eugene, Oregon. Matheson who ran the lead off legs on the mixed 4x400m teams in the semis and finals, clocked 46.40 seconds. (Photo: Paul Reid)OREGON, USA — Jabari Matheson will run his fourth 400m over the first two days of the World Athletics Under 20 Championships when he lines up in the individual semi-finals of the distance in the afternoon session Thursday. Daniellia Dixon and Shamieka McLean also qualified for their women’s 400m semi-finals after the morning’s first round. McLean, who was part of the mixed 4x400m team that ran the first round, was third in her first round heat in 53.95 seconds.