Williams injured his shoulder in the Heineken Cup victory in Benetton Treviso in December and was forced to seek the advice of specialists before giving the injury two weeks complete rest. Although there was only one trademark run from the wing against Munster, he successfuly negotiated the full 80 minutes without any problems.
"It has been really a really frustrating time for me, but I'm just grateful to be back so soon. It could have been far worse," said Williams, a 2005 Test Lion.
"I could have been out for anything between two and five weeks. You just never know with an injury.
"I had a lot of scans and two injections on the shoulder to stop the inflammation, so I'm just relieved to be back in two-and-a-half weeks."
After a sensational 2008, in which he broke Gareth Thomas' Welsh try scoring record, helped the Ospreys win the EDF Energy Cup and steered Wales to a second Grand Slam in four years, Williams looked like being a certainty for Ian McGeechan's British & Irish Lions squad for this summer.
But the injury cast a few doubts in Williams' own mind about whether or not he would be ready for the championship - and be fully fit when the Lions management announcement their advanced guard of 60 players on 20 January.