The 24-year-old Middlesbrough skipper, who has 10 international caps, believes the time has come to make a statement, as much to himself as anybody else.
Last seen in a Socceroos shirt against Scotland in August last year, the same month he broke down with a serious ankle-ligament injury, Williams is likely to be paired alongside skipper Lucas Neill against the 33-ranked Romania at Malaga’s Estadio Ciudad.
He has played right-back, midfield and stopper for Championship promotion-chaser Boro this season and will be happy to play anywhere for his country – so long as he performs up to his own expectations.
'I am probably one of my strongest critics and I don’t think the national team has seen the best of me by a long way," admitted Williams.
'I set high standards for myself, I have always been very self-critical and I haven’t reached the level I want to yet for my country.
'Obviously I have missed the chance to play games through injury but when I have played I don’t think I’ve really been at my best yet.
'Hopefully, if I get the chance to start against Romania I can begin remedying that and producing the sort of form I know I am capable of."
Williams, who was sidelined for four months before returning to action just before Christmas, is also critical of his club form, citing possible rustiness from his long lay-off.
'I’ve made a few errors, which are a bit uncharacteristic, and I think some of that is down to feeling my way back and I’m working hard to rub of those out of my game," he conceded.
'It’s just good to be playing again, though. As people know I’ve had my fair share of injuries and I’m hoping they are behind me now.
'I’m just looking forward to getting down to Spain, to linking up with the lads and making up for lost time with the national team."
Williams is not overtly pushing to partner Neill against Romania as coach Holger Osieck seeks to find the right combination leading into the final four AFC Group B FIFA World Cup qualifiers against Oman, Japan, Jordan and Iraq this year.
But he would relish the opportunity, should it come.
'Lucas is the consummate professional and it would good to play alongside him and learn a few things on the way," he added. 'I am sure we could get a good understanding going if the boss wants to go that way."
He has yet to discover a penchant for any one position.
'I haven’t really worked out where I am best suited yet," he added. 'I’ve played a few roles for Middlesbrough this season and while eventually I would like to settle on one spot, I am not there yet."
Williams insists that Boro remains in the hunt for an automatic promotion spot despite slipping to three successive league defeats.
And there is also the bonus of an FA Cup fifth-round tie against either Brentford or Chelsea looming this month.
'I think the slip in our league form is a blip but we obviously need to turn it around," he said of Boro’s slide down to sixth, three points off an automatic promotion spot.
'You have your ups and downs and people sometimes forget how difficult this division is. But we still have quality and the confidence is definitely still there."