Paul Brizzel became the fourth Irish track and field athlete to fail to make it out of the first round of their discipline at the Olympic stadium, but still managed a season's best of 21.00 seconds in his 200m heat.
The Ballymena and Antrim clubman, national record holder at 100 and 200 outdoor, finished sixth in the first heat with four to qualify for this evening's second round.
Drawn poorly in lane one, the 27-year-old beat out his previous best of the year of 21.03 with a strong second hundred, but faltered in fifth with Swede Johan Wissman outpacing him.
Stephane Buckland of Mauritius won in a time of 20.29, with Athens 100m silver medallist Francis Obikwelu of Portugal second, in 20.40.
Brizzel qualified for the Games at last year's World Championships in Paris (20.56), but showed little form last month, when losing his national 200m crown to Galway youngster Paul Hession in Santry.
Result:
Men's 200m, Heat One - (Four to progress to second round; plus four fastest losers)
(1) Stephane Buckland (Mri) 20.29, (2) Francis Obikwelu (Por) 20.40, (3) Juan Pedro Toledo (Mex) 20.40 (NR), (4) Yaozu Yang (Chn) 20.59 (SB), (5) Johan Wissman (Swe) 20.60, (6) Paul Brizzel (Irl) 21.00 (SB), (7) Nabie Foday Fofana (Gui) 21.45