Mark English has failed to progress to the semi-finals of the men's 800 metres in Toyko after finishing fourth in his heat.
The Donegal runner posted a time of 1:46.75, which was 0.16 seconds behind Polish runner Patryk Dobek in third place.
The 28-year-old's time - over two seconds slower than the Irish record he ran last month - was not good enough to secure a place as one of the fastest outside of the top three automatic positions in each of the six heats.
In a physical race, which saw the Dominican Republic runner Dennick Luke fall to the ground and English collide with French runner Benjamin Robert, the Irishman was unable to get out early enough to build momentum for a strong finish.
Speaking afterwards a disappointed English was able to positively reflect on his 2021 season as a whole saying: "Coming into the year, my two goals were to qualify for the Olympics, and get a new Irish record, and I did that."
Looking to the future, English has his eyes set on next year's World Championships, having already secured his place, adding: "I’ll get back training for them in a couple of weeks, there’s nothing else I can target at the minute."
A new winner of the event is set to emerge in Tokyo for the first time since 2012, after double Olympic gold medallist Kenyan David Rudisha's persistent injuries denied him the chance to defend his title, kicking the race wide open.
Botswana's 2012 Olympic silver medallist Nijel Amos, who boasts this year's world leading time of 1:42.91, advanced to Sunday's semi-finals by winning his heat with a 1:45.04.
Amos defeated France's Pierre-Ambroise Bosse, the 2017 world champion, who faded badly towards the end, failing to qualify after finishing sixth, even though he had been leading the race halfway through.
Kenya's Ferguson Rotich, also comfortably made it through to the semis, winning with a time of 1:43.75. The 2019 world bronze medallist, trailed after the bell, but a push in the last lap helped him to overtake the leading pack to win.
Another Kenyan, Emmanuel Korir, who boasted this year's second-fastest run, just edged it to win his heat and advance to the next round.
Meanwhile, Olympic bronze medallist five years go in Rio, American Clayton Murphy strolled through to the semi-final confidently winning his heat with a time of 1:45.53.
