In the middle of the ninth round, with Vargas ahead on all scorecards, the two fighters' heads came together in what seemed like an innocuous clash.
Gory images show the 32-year-old's ear nearly split in half from the top, hanging sickeningly from the side of his head. He later tweeted that he had been to hospital, where he received stitches before boarding a plane home to the UK.
One would imagine after a period of rest on the ear that he will be chomping at the bit again to get back into world title contention in 2018. "Have a good Christmas everyone", he wrote.
The split down Smith's ear was so bad that the fight had to be stopped - and rightfully so.
Whoa, I had no idea Mike Tyson was still in the ring.