While England struggle to decide whether Durham's Paul Collingwood or Lancashire's James Anderson should come into the XI for today's Ashes decider, Australia received a much-needed boost with first-choice new ball bowler Glenn McGrath declared fit to play.

Without him, penetration and control have been lacking in equal measure, so much so that Michael Vaughan's men have passed 400 in their first innings in three consecutive matches: the first instance of Australia undergoing such a trot since they last lost an Ashes series, 18 years ago.

When McGrath is in the side, Australia win two out of three Test matches compared to a success ratio of less than one in every two when he is not and Ricky Ponting hailed his ability to function in a dual role.

The Aussie skipper has been outspoken over the use of substitutes this summer but admits having McGrath back for the Ashes finale will be like playing with 12 men.

Australia captain Ponting was given the good news on the eve of a contest his team have to win to retain their hold on the old urn when McGrath came through a fitness test on his sore right elbow.

McGrath, 35, replaces Michael Kasprowicz for the crunch encounter, after missing both games England have won in the series to date - he has taken 14 wickets in the two he has played.

''It is a very positive sign for us,'' said Ponting. ''Every time he misses a game we miss him greatly. He almost plays as two bowlers in our team.

''He is the main strike bowler up front with the new ball and and at the same time you can call on him to bowl some tight overs later.

''He is a vital part of our side and someone who has done well for us over the years, especially in big games and this is what this has been built up to be.''

McGrath, whose 513 victims at the top level include 131 Englishmen, was ominously brief when he said: ''It's business as usual.''

That is not quite true, however, for Australia are in a position they are unaccustomed to in modern times; needing to win to save a campaign.

Should they return home as the first Australian side to lose to the old enemy in nine series, it could signal a raft of changes.

Yet Ponting suggests his position as captain should be fireproof and some of his senior counsel should also be spared.

''We set very high standards for ourselves and if we happen to lose this series I am sure we will cop a bit of a hammering,'' said Ponting. ''Maybe we should.

''We have given it our best shot. We haven't been good enough just yet but we have one game to change everything. I wouldn't like to think my position is under threat.

''I am the first one to admit when I make mistakes, I always have been. I could have done things slightly different at times but Michael Vaughan will probably say the same thing and they are in a winning situation right now.

''We all share responsibility for where we are, I know as captain I will take a bit more, that is what it's all about in any sporting team.

''A few of the senior players might be playing their last Ashes series in England, that within itself will be enough motivation for them.

''I wouldn't like to think anyone is playing for their career in this game.''

Ponting has already addressed his colleagues about the severity of the situation but urged them to draw on previous experience in their bid to overturn their poor form.

''Our stats so far in this series are not great, that would indicate England have had us under pressure,'' Ponting declared. ''That is not the first time this has happened in our careers and that is something I have stressed to the players all week.

''The batsmen have made close to 100 Test centuries between them and you can't tell me we haven't been under pressure at different times for every one of those.

''Now it is a question of doing it on the big stage when it really counts.''

Teams: England (from): MP Vaughan (captain), ME Trescothick, AJ Strauss, IR Bell, KP Pietersen, A Flintoff, GO Jones (wkt), PD Collingwood, AF Giles, SJ Harmison, MJ Hoggard, JM Anderson.

Australia: RP Ponting (captain), MJ Hayden, JL Langer, DR Martyn, MJ Clarke, SM Katich, AC Gilchrist (wkt), SK Warne, B Lee, GD McGrath, SW Tait.