The 31-year-old also had three teeth knocked out and was left with a two-inch cut above his eye.
Police are now investigating and appealing for witnesses to the assault at about 10pm on Friday in the courtyard of the Three Sisters pub in Cowgate.
A police spokeswoman said: “The injured man suffered serious facial injuries and was taken to Edinburgh Royal Infirmary for treatment.”
The suspect is described as white, in his 20s, of muscular build with short fair hair shaved at the back and sides.
He was wearing a white shirt with rolled up sleeves and light coloured trousers.
After attacking his victim, he walked off towards the Grassmarket.
Anyone with information should contact Gayfield CID on 101 quoting incident 4514 of 21st December or Crimestoppers anonymously on 0800 555 111.
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