Tom Daley conceded he could not feel lower after his shock failure to make the 10 metre platform diving final at Rio 2016.
Great Britain's Daley compiled a personal best score of 571.00 in the preliminary rounds on Friday - the best score of any competitor.
However, below-par efforts with his second and third dives left the two-time bronze medallist with catching up to, but he was left last after botching his final dive, to finish over 150 points behind leader Chen Aisen, whose 559.90 was well off Daley's previous benchmark.
Asked if Saturday's shock was the low point of his career, Daley said: "Oh yeah, it doesn't get any lower than this.
"It is tough to even think about what the final is going to be like later and what the scores are going to be because if the scores are not over 571.00, it will be even more frustrating.
"It's just really tough to think how well it went yesterday and if I'd just done that 24 hours later, managed to do it in the final, it could have been an Olympic gold medal around my neck, but instead it's the heartbreak.
"I really don't have a reason. I've been diving like I've been diving last night for the last three weeks leading up to this and that's why it's so hard to take in.
"I'm kind of in shock right now because I know that I could win that gold medal and I think right now I'm the only one that could challenge the Chinese for that gold medal."