England and Australia will add to cricketing history on Thursday in playing the first one-day international featuring substitutions and experimental fielding restrictions.

That novelty, however, is unlikely to deflect Michael Vaughan and Ricky Ponting from their main aim.

The Headingley match, the first of three one-dayers before the start of the Ashes next month, is yet another skirmish before the main battles ahead but will still provide more opportunities to probe for weaknesses while scoring psychological points.

Both captains know that the winners of the one-day series will be all but forgotten within a matter of weeks. It is the test matches that carry the status.

To date, England probably feel they have performed better than they expected against the world champions. The teams won one game each in their head-to-heads during a triangular series also involving Bangladesh, with a third encounter washed out, before playing out a dramatic tie in the Lord's final on Saturday.

Vaughan's one-day side are still very much work in progress and have come nowhere near to emulating the successes of the test team, who remained unbeaten throughout 2004. But to beat Australia and then to level a game in which they had been reduced to 33 for five chasing 197 to win suggests progress.

After the final, Australia fast bowler Glenn McGrath, normally as miserly with his compliments as he is at conceding runs, praised

England's new combative spirit, as well as lauding his opposite number Steve Harmison.

England coach Duncan Fletcher, also seeking long overdue positives, believes the Australian batsmen are showing signs of uncertainty, with Ponting's tendency to fall over to the on side and play across the line at the heart of their problems.

Australia coach John Buchanan, however, begs to differ. He suggested after the Lord's tie that Fletcher would do well to "reflect on how Trescothick has got out, how Strauss has got out, how Vaughan has got out through the course of the series so far with the test matches in mind".

Brett Lee, bowling at the top of his form and pace, and McGrath feel they have their measure.

Marcus Trescothick, whose immobile batting technique has been unpicked before by the Australians quicks, scored a century, a half-century and 43 against Bangladesh in the triangular series but failed to get to 20 in four starts against Australia.

Andrew Strauss is averaging 11.5 against the world champions. Vaughan has one half-century and one duck against them.

In truth, Vaughan and Ponting look as off-colour as each other. In the teams' only other meeting, a Twenty20 jamboree, Vaughan was out first ball while Ponting lasted three.

On Thursday, England and Australia will be allowed to make one substitution each at any stage. This is likely to help sides batting second, since most substitutes will be batsmen or batting all rounders and thus of little value to teams batting first, who need to keep their

bowlers.

There will also be 20 overs of fielding restrictions rather than 15, with 10 at the start of the innings and two more blocks of five overs each, to be introduced at the fielding captain's discretion.

The England and Australia captains, however, may have most of their attention on other things at Headingley -- on scoring psychological points and, almost as important, on scoring a few runs into the bargain.