The Coventrian ran in Lane 2 in a strong line-up including Jamaica's Usan Bolt and USA's Wallace Spearman, who finished one and two with Kim Collins third.
Devonish, who looked clearly in pain was upto fourth but dropped back to finish seventh in a time of 20.57
"I was diappointed," said Devonish to the BBC after the race. "I have been pushing in training but did not get the shape.
"I'm a bit lost for words.
"Today was rubbish but I needed more time. I am better than what I did today."
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