Wasps refused to publicly discuss the matter but Powell has now spoken out about the unsavoury incident with a group of football fans.
"I was knocked to the ground by a gang who then started to kick and punch me," Wales international Powell told The Telegraph.
"It was pretty scary. I curled up into a ball and put my hands over my face and temples but couldn't cover the back of my head.
"I was then hit by a bar stool and lost consciousness after that but I suffered a pretty bad cut. There was blood everywhere. I think I lost around two pints of blood in the pub and was taken away in a wheelchair and then taken by ambulance to a hospital where they stitched me up."
The incident, which happened at the Walkabout pub in Shepherd's Bush Green on Monday night, is currently being investigated by police.
However, Powell, who missed out on a Test place with the Lions two years ago, has insisted he will not be looking to take the matter any further.
"A load of QPR fans came into the pub after their match and I think they heard my Welsh accent and started giving me a bit of stick," Powell added.
"We started singing a few songs and exchanging a bit of banter but then it all kicked off.
"I needed at least 10 stitches but I am okay now. I am feeling sore all over, but it was just one of those things.
"I was asked by the police afterwards if I wanted to press any charges but I said I just wanted to forget about it and move on."