Athlete Katarina Johnson-Thompson says she is "full of regret" that she didn't break the pentathlon World Record.
She won a gold medal, and even broke the British record set by Jessica Ennis-Hill, but the World Record is still held by Nataliya Dobrynska from Ukraine.
To break the record, Katarina would have had to run the 800m section of the pentathlon in under 2 minutes 11 seconds.
Katarina told BBC Sport: "This is a huge breakthrough, but I am full of regret from the 800m."
She said: "I thought I could easily run that time and maybe took it for granted. It could've been a different story. I should've been able to do that."
What World Record would you like to beat?
I'd break the record for the most goals scored in one minute.
I would break the record for the fastest swimmer, I love swimming.
I would like to beat the world record for the longest pogo stick time.
I would like to break a world record to do with running.
I would like to break the record for most drumming in one hour because I am amazing at drumming!
I would like to beat the longest swim record because I enjoy swimming lots!
I would break the world record for the slowest time eating jelly.
I would love to try and set a record for highest vertical jump.
I would break the most hot dogs eaten in a minute.
Ruby, Whitley Bay
I would like to beat the pentathlon record.
I'd eat the most chocolate in one minute.
I would like to break the world record for longest swimmer.
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