Ahmet Patterson suffered injuries to his head and right eye after being struck by a brick while running
Image credit: PA Sport
The 29-year-old suffered injuries to his head and right eye after being struck by a brick while running past a group of men in London on Thursday night.
Patterson said: "I was doing my road work when I noticed a group of men gathering on the pavement around 50 yards in front of me.
"I tried to run around them but they moved in front of me and blocked my path.
"As I ran around them one of the men struck me in the face with a brick and we got in a scuffle. Once I started defending myself they ran off."
The injuries sustained left Patterson with no choice but to withdraw from his challenge for the Lonsdale Belt at the Motorpoint Arena in Cardiff.
Welshman Williams will now face Hungary's Gabor Gorbics on the same bill.