The loanee faces a spell out after sustaining an injury last Saturday in their 2-2 draw at home to Millwall.
Sounds like Jonny Williams has injured his shoulder again. Possible surgery. Needs a bit of good luck to go his way.— Phil Cadden (@pjcadden) November 21, 2017
The 24-year-old took to Instagram to thank supporters on his latest setback.
"Op went well. Thank you for all of the caring messages and support, it means a lot.
"Had a few tough setbacks that I have had to come back from already and this is probably the hardest to take.
"On the mend now and looking forward to getting back doing what I love asap."
Williams has made ten appearances for the Black Cats this season as the side from up north look to bounce back immediately to the top flight, however it hasn't gone to plan with Simon Grayson already being shown the door.
However, Chris Coleman has arrived at the Stadium of Light, and as his former international manager, Jonny Williams will relish the opportunity to link up with his old boss who left the Wales job this month.
His target now will be to recover as soon as he possibly can, to get considered for selection, and no doubt he will be a firm starter under Coleman who has seen him shine in the national colours.