For the past week, it has been just like old times: Rupert Murdoch, shirtsleeves rolled up, bossing the newsroom of the country?s leading tabloid newspaper as if he had not been away building his media empire in America for much of the past 30 years,

as if the impact of the phone hacking and police bribery scandals embroiling his British newspapers could be rolled back by the sheer force of the proprietor?s will.

Murdoch, who will turn 81 in two weeks, has taken on-the-spot command of the project he announced after flying in from New York 10 days ago: After more than 40 years as a Monday-through-Saturday paper, the rambunctious tabloid he built into the country?s richest and most widely circulated paper, The Sun, is becoming a seven-day-a-week operation, publishing this Sunday for the first time.

But The Sun on Sunday is more than a new step down the path Murdoch has worn as a newspaper pioneer ? and it has more in its implications for the News Corporation, the $40 billion company he built from his long-ago start as the owner of two newspapers in Australia, than the relatively modest gamble in terms of start-up money, many newspaper analysts say.

For Murdoch, and the staff at his British publications, the true significance of the new Sunday paper seems to be that it, in effect, draws a line in the sand. With the founding of The Sun on Sunday, Murdoch appears to have declared that his tabloid will not be hounded into oblivion by the opprobrium that has beset The Sun and The News of the World, the weekend tabloid he shuttered when the phone hacking scandal broke wide open. About 30 of the papers? current and former employees have been arrested and released on bail on suspicion of criminal wrongdoing in the hacking and bribery scandals. Murdoch raised the battle cry in an e-mail to The Sun?s staff he drafted last week as he crossed the Atlantic in his corporate jet. ?Having a winning paper is the best answer to our critics,? he said, announcing the new Sunday paper.