Martin Johnson confirmed that Danny Cipriani would be turning his back on an England career if he completes a proposed move to the Melbourne Rebels.
Cipriani, the Wasps fly-half, is out of contract in the summer and was approached by Rebels representatives Rod MacQueen and John Connolly last week as part of the new Super 15 franchise's recruitment drive.
Should Cipriani complete a move to Australia, he would be unavailable for the 2011 Six Nations and therefore almost certainly out of Johnson's Rugby World Cup plans.
Asked whether Cipriani could remain part of the elite squad when based in Melbourne, Johnson said: "No of course it's not.
"The seasons are the same. They are playing through February and March so he wouldn't be available for England during the Six Nations.
"It is his choice. If he wants to do that, it is up to him.
"It is impossible for him to play for England in the Six Nations if he is over there. I am sure he understands that."
Reports today stated Cipriani had plumped for a shock move Down Under because he had been told there was no future for him in Johnson's England set-up.
Johnson insisted his relationship has not broken down with the 22-year-old, who will start at full-back for the Saxons against Italy A on Sunday.
But Johnson admitted he had made no effort to speak to Cipriani or persuade him to stay.
"I am aware of the situation but I have not spoken to him directly about it," said Johnson.
"All I have heard are rumours that he could be signing. Until there is anything concrete he is in the Saxons team in Italy."
When Cipriani exploded onto the scene as a precociously talented teenager with Wasps, he was considered the heir apparent to Jonny Wilkinson as English rugby's next golden boy.
That feeling was only strengthened when Cipriani replaced Wilkinson as England's fly-half and made a match-winning full debut against Ireland in the final match of the 2008 Six Nations championship.
Cipriani was rushed straight back into the England side for the 2008 autumn internationals after recovering from a gruesome ankle fracture.
But Cipriani struggled for form and was dropped to the bench after three Test starts and he then fell off the radar altogether.
Rumours abounded that Cipriani had fallen out with the England management amidst a clash of personalities.
They were denied from both sides - but Cipriani won the last of his seven international caps in 15 months.