The Crystal Palace midfielder played for 85 minutes against Andorra on Tuesday as Chris Coleman's squad celebrated their qualification with a comfortable win in Cardiff.
Will that be enough to see him start for the Reds at Bristol City this Friday night as the Championship resumes following the international break.
Speaking about his groin muscle problems, Williams is quoted on the official CPFC website as saying: "I've got no doubts with it.
"I've played the most games I've played in a year now, including under-21s games, so hopefully I can just kick on now and play more and more."
He could be joined in the Nottingham Forest squad soon by another loanee midfielder as Liam Trotter of Bolton Wanderers is poised to switch clubs.