Adam Peaty was already a world record holder - but he just beat his own time by 0.37 seconds to finish the 100 metres breaststroke in 57.55 seconds.
And everyone's chuffed for him on Twitter.
Congratulations @adam_peaty you smashed it bro!!! That Gold is yours.
-- Jaykae (@jaykae_invasion) August 6, 2016
Adam Peaty is a class act, just obliterated his own world record in the heats.
-- philip wright (@philwrig) August 6, 2016
-- Mat Twells (@twellsym) August 6, 2016
The 21-year-old is hotly fancied to become Britain's first male Olympic champion in swimming since Adrian Moorhouse in 1988 - and people just love his chilled out attitude towards it all.
-- Daniel Eckersley (@dan_eck) August 6, 2016
Adam Peaty is a bro, literally just broke the world record and was the most chill person in the room ?
-- Jordan Holder (@jordan_leigh) August 6, 2016
-- Georgina Free (@free_georgina) August 6, 2016
Guess it must be pretty good to know you're the best in the world at something... twice.