Williams enjoyed an incredible year in 2008 when he picked up numerous awards, including the IRB World Player of the Year title, for a series of stunning performances for club and country.
2009 has not be so kind to the Welsh wing, however, as injuries have curtailed his game time and his form has not reached the meteoric heights of last year.
With the Ospreys crashing out of the Heineken Cup in humiliating fashion last weekend and Wales only managing a fourth-place finish in the 2009 Six Nations, Williams has not had too much to shout about over recent weeks.
A place in the Lions squad for the three-match series with the Springboks would be a great way to get over those disappointments but the 32-year-old says he is far from confident of being named in Ian McGeechan's touring party this coming Tuesday.
"It's in the back of my mind and I don't think anyone who hasn't played well will feel they are definitely going on this trip," said Williams.
"There are a lot of players in the United Kingdom putting their hands up at the moment and the squad doesn't get announced until the very last possible minute."
Whatever happens during Tuesday's squad announcement in London, Williams is determined to end the season on a high with the Ospreys.
Former Wales coach Scott Johnson arrives as director of rugby this week ahead of the derby clash with the Scarlets on Saturday and Williams is desperate to help the Ospreys return to winning ways.
"It's not falling apart at all. We're as strong as ever and probably even more determined after recent results," added Williams.
"The league is still to play for and there are no panic stations. We've played some good rugby this season and some not so good. We need to be more positive and learn from our defeats."