Botswana's Isaac Makwala has the chance to go for World Championships gold today, but he remains aggrieved at his exclusion from his favoured 400 metres on medical grounds.
Makwala overcame illness, quarantine and two races in little more than two hours on Wednesday to qualify third quickest for the 200m final.
He had to run a solo time-trial at 6.40pm on Wednesday to advance to the semi-finals at 8.55pm, where he was an additional competitor and qualified for the final.
But the manner of his exclusion from Tuesday night's 400m final still rankles.
Makwala told the BBC: "Yes, I'm running with anger. I still want my 400. That's my race.
"I'm still running heartbroken. I wish the IAAF had taken the decision for me to run my 400 first, alone. I was ready to run the 400 alone. Then I could run the 200.
"I don't know who took the decision for me not to run my final 400 - 400 is the race that I'm training for. The 200 I race sometimes.
"I wish to thank the IAAF for giving me another chance and the crowd is so amazing. They made me believe. I just want to thank this crowd. It's so amazing."
The spectators arriving early at the London Stadium saw Makwala's time-trial 25 minutes before the scheduled start to the evening session. It took place in chilly temperatures and torrential rain, but Makwala delivered.
He had to clock 20.53 seconds or less to run again in the semi-finals and did so with ease, finishing in 20.20secs before celebrating by doing press-ups.
And Makwala put his right arm aloft in celebration after finishing his semi-final heat in second place, behind the United States' Isiah Young, the fastest qualifier in 20.12.
Makwala was running in lane one - not normally used for the event due to the tightness of the bend - and clocked 20.14.
The anticipated duel with Wayde van Niekerk will now take place over half the anticipated distance.
Van Niekerk, the Olympic 400m champion, received his world 400m gold just a few minutes after Makwala's time-trial.
And the hanging around may have contributed to his performance as he squeezed through to the 200m final as the second of two fastest losers in 20.28.
Illness has affected numerous World Championships contenders and Makwala had been given medical dispensation to withdraw from the 200m heats on Monday night.
Without a valid reason for pulling out, he could have been disqualified from the 400m final - an event he was forced to miss under protocols imposed by Public Health England.
His 48-hour quarantine expired at 1400BST on Wednesday afternoon and the IAAF accepted a request from Botswana to allow Makwala to try to qualify for the shorter event.
That suggested a softening in relations between Botswana and athletics' world governing body after a strained 24 hours.
Video footage on Tuesday night showed Makwala was prevented from entering the warm-up track and Botswanan officials criticised the IAAF for its heavy-handedness and lack of communication over cases of norovirus which have struck at the championships.
The IAAF had earlier been forced into a further rebuttal to claims from Makwala that "sabotage" led to his exclusion from the 400m final.
Makwala told ITV on Tuesday night "maybe this is sabotage" and told the BBC on Wednesday "there's something fishy they don't want to tell us".
However, the IAAF dismissed his allegations as "absurd".
An IAAF spokesperson said in a statement to Press Association Sport: "There is nothing we want more than extraordinary competition at these championships.
"We freed up the competition schedule here to allow this to happen between these two athletes over 200m and 400m. To suggest otherwise is absurd."