1. Tomi Juric (striker)
The former Western Sydney Wanderers star, now playing for FC Luzern, has made big strides during this campaign and now needs to make even bigger ones to help ensure Australia get through.
Juric was particularly effective in the opening qualifier against Iraq in Perth on September 1. He provided a beautiful ball from the right for a Massimo Luongo goal and scored himself.
That obviously augurs well for the return game against Iraq in Tehran on Thursday night.
2. Maty Ryan (goalkeeper)
Two teams go through automatically and one heads into a series of playoffs. A critical save, just like a critical goal at the other end, could make all the difference.
Ryan, back playing regular football again after switching leagues in Europe, is in form, including a crucial penalty save as his Belgian club, Genk, qualified for the Europa League quarter-finals.
He has already made key contributions in this campaign, with great saves at 1-1 against Japan and again at 2-2 against Thailand ensuring Australia at least got out of those games with a point.
3. Mile Jedinak (midfielder)
Opposition players have tried to put him off his penalty-taking process by using delaying tactics, or been prepared to gamble on creeping inside the box and getting into his peripheral vision as he moves in to take the shot, but nothing seems to faze him.
Jedinak must have ice running through his veins and let's hope it stays that way, because, who knows? He might have to step up to take one of the most crucial penalties in Socceroo history at some stage during these last five games.
4. Tim Cahill (striker)
The veteran will be an important player on the bench if Australia desperately need a goal in the last half-an-hour, or even just to come on and harass opposition defenders and make it difficult for them to get things moving in attack if the Socceroos are in front.
Cahill replaced Tomi Juric in the 71st minute of the away game against UAE on September 7 and four minutes later he was on the end of a cross from Brad Smith to calmly score what was the only goal of the match from the edge of the six-yard box. He is a weapon Australia simply must have in store.
5. Brad Smith (left back)
Smith is a marauding player from fullback down the left, which is just how coach Ange Postecoglou likes it. He gives the attack quality width, which the Socceroos haven't always gotten from their wide men in the front-line during this campaign.
Smith also sent in the cross that led to Tomi Juric being bundled over for a penalty that Mile Jedinak converted in the 1-1 draw against Japan at Etihad Stadium on October 11. He has got a lot of energy and the Socceroos are going to need his damaging runs.