Justin Gatlin has conceded that he could do no more after being pipped to another world title by rival Usain Bolt on Thursday.
The American, 33, finished second to his Jamaican counterpart in yesterday's 200m final in Beijing, having also lost to the 29-year-old in the 100m on Sunday.
"I went in there with my gameplan," he told reporters.
"When you are known to be a front-runner and he is a front-runner, it is a weird feeling to have someone next to you or in front of you.
"You have just got to make sure you stay focused on your race. I think I did the best I could."
Earlier this morning, Gatlin warned Bolt that he will travel to Rio next summer determined to go one better and strip the 10-time world champion of his Olympic titles.