Olympic champion Mack Horton has thanked an anonymous spectator who potentially saved his life by noticing an abnormal mole on his chest.

The Australian swimmer, who won a gold medal in the 400m freestyle at this summer’s Rio Olympics, revealed that someone had watched him on television and subsequently contacted Australia’s Olympic swimming team to raise their concerns.

Horton has since undergone surgery to have the melanoma removed.

In a photo he posted on Instagram, in which he sports a post-op bandage, he wrote:

“Shout out to the person that emailed the swim team doctor and told me to get my mole checked out. Good call. Very good call.”

Well done to those anonymous eagle eyes!