The American swimmer who has 23 Olympic medals in total inlcluding today's medal. USA defeated France and Australia to bag the gold.
The entire world was excited as Phelps started his Rio Olympics 2016 campaign on a high as all eyes were on him.
After the win several snaps were taken of the swimmer which also depicted bruise marks on Phelps' body. He had a prominent mark on his shoulder and 3 more on his back.
Fans around the world were confused as they failed to understand the bruise marks.
The mystery has been finally solved after it was revealed that the marks are a result of a healing and conditioning practice called 'cupping'.
It is a type of Chinese medicine that claims to relax muscles and reduce physical pain. Cupping, as the name suggests, involves glass cups.
These cups are heated and placed on the body, where they create a localized suction on the surface of the skin. This, according to several people, is said to stimulate the flow of blood and thereby helping to treat pain.
'Cupping' apparently reduces muscle strain. That is why it is used as physical therapy by a number of athletes.
So Michael Phelps fans can relax now as the player is fit and fine and is ready to compete in individual categories and break records.