A lively personality with a winning grin and a word for everyone, Williams' sunny disposition has, no doubt, helped in the first 26 years of his life. And those are the characteristics that will serve him well long after his footballing days are gone.

But the question has to be asked: is he anywhere near ruthless enough on the pitch?

Williams should be at the peak of his powers. He is blessed with pace, good technique and an unpredictability that can make him hard to match-up. But he can also disappear from games and have little or no impact. Hot and cold barely does justice to some of Williams' performances during his time at Melbourne City, which he joined in 2011 from the wreckage of North Queensland Fury after a brief spell with Sydney FC.

Since then, he has been in and out of the team as coaches John van 't Schip, then John Aloisi and now van 't Schip again have sought to harness the undoubted potential and ability the Queenslander, one of the few indigenous players to have represented his country, possesses.

But Williams will have to step up now, given the striking problems City is facing as it prepares for life without David Villa.The Spanish World Cup winner and ex-Barcelona and Atletico Madrid star, has been a lifesaver for City in the opening two rounds of the season.

The guest player equalised against Sydney when City had dominated the first half only to fall behind to an against-the-run-of-play goal from Corey Gameiro, then levelled late in the home game against Newcastle at AAMI Park last Sunday when a shock defeat loomed.

Williams missed the first game of the season, but played against Newcastle. He was his usual industrious self and worked and ran hard. But the one good chance that fell his way – a volley from inside the penalty area right in front of Mark Birighitti – was spurned when he took the ball on the volley and fired over.

It's not just Villa's absence – he returns to New York after the round-four clash with Adelaide with City officials hopeful he will return to see out the remaining six games of his 10-match stint – that Williams will need to cover.

Robert Koren, the vastly experienced Slovenian captain and a former Premier League attacking midfielder, is another whose absence van 't Schip will feel keenly. Koren injured his calf in the lead-up to the opening round against Sydney and has not played. MRI scans earlier this week indicated the injury was worse than feared, and he could be out for a further three to four weeks.

After that, he will need to train intensely to bring him up to game readiness, so even if things went well it would be December before he was likely to pull on a City shirt and a couple of outings before he really hit match fitness.

Koren was a player van 't Schip had pinned his hopes on to weigh in with goals from midfield. He had been a regular scorer in the Premier League during spells with Hull City and West Bromwich Albion, and his smarts and finishing ability would surely have seem him become a threat here.

He may still do so, of course, but his injury doesn't solve van 't Schip's immediate problems nor take the pressure off Williams.

The coach could look to Mate Dugandzic as an option, but the forward is more of a wide player and creator than out-and-out attacking option. The winger has been on target 11 times in 58 appearances for City/Heart, but his goals tend to come in spurts rather than on a regular basis.

Damien Duff, the ex-Chelsea and Fulham man and former Republic of Ireland international, is an occasional, rather than regular scorer. His Premier League record suggests he might score every eight or nine games, and while the standard in the A-League is less demanding he is now 35 and plays more as a provider than a striker.

Something similar can be said of the other midfielders in the City squad. Aaron Mooy has netted some spectacular goals in his time – a fiercely struck drive from 30 metres for the Socceroos against China in the East Asian Cup last year is a particularly strong memory – but, again, they are characterised by their rarity.

Massimo Murdocca's goals from midfield are so infrequent they are probably worth a feature on their own, while James Brown, another attacking midfielder, is hardly profligate. The 24-year-old was a regular marksman at Gold Coast United, but in 28 appearances for the Jets and a further two for City he has yet to hit the target.

City's possession-based game and commitment to attack, plus its plethora of creative midfielders, mean the team is always likely to create opportunities. Without Villa, it desperately needs someone to take them.

Williams will never have a better chance to prove his worth. And with the Socceroos lacking firepower aside from Tim Cahill and the Asian Cup looming, there would never be a better time to take that opportunity.