Fredericks came third in the first semi-final in 20.29 seconds, 0.26s slower than winner Darvis Patton of the United States. Stephane Buckland of Mauritius was second in 20.11s.
In the second semi-final, John Capel of the United States won quite comfortably in 20.18s, followed by Shingo Suetsugu of Japan in 20.22, Darren Campbell of Great Britain in 20.34 and Uchenna Emedolu of Nigeria in 20.44s.
Photograph: Getty Images