No televised testimony has been so eagerly awaited in Washington's corridors of power since Monica Lewinsky was questioned about her relationship with Bill Clinton. And while the witness who will raise her hand before the cameras on Thursday and swear to tell the truth and nothing but could hardly be more different from Monica, in one respect they are similar: her evidence, too, has the potential to cripple a president.
Condoleezza Rice is America's first woman National Security Adviser - the official whose job it is to interpret and inform the President on all aspects of US foreign policy and security. George Bush's confidante on everything connected with "abroad", she is variously described as a "lightning brain" and a "ferocious intellect"; the most frequently heard description is "brilliant".
This week, however, Dr Rice - who has followed the first woman Secretary of State, Madeleine Albright, in choosing to use her academic title in her government job - faces one of the most testing days of her career. She has been called before the commission investigating the 11 September terrorist attacks to respond to a battery of damaging charges levelled by the former White House counter-terrorism chief Richard Clarke. She will need all her intellectual resources to parry them, and a good deal of political skill.
Mr Clarke's central accusation is that the Bush administration misread the threats facing the United States before 11 September. This, he claimed, was because officials ignored what their predecessors from the Clinton administration had told them about terrorism, because they were stuck in a cold-war mentality that saw long-range missiles and rogue states as the most immediate danger, and because they were completely, and mistakenly, fixated on Iraq. Directly and indirectly, Mr Clarke was particularly critical of Ms Rice, who - he suggested - appeared not to have heard of al-Qa'ida when he first briefed her, and had never taken the threat from terrorists, as opposed to states, seriously enough.
Given the shock that Americans still feel from 11 September, the changes levelled by Mr Clarke were harmful enough in themselves. But in a few short sentences, Mr Clarke had also done what no one had dared to do, probably since Dr Rice's student days: he had publicly dared to challenge her competence and her professional reputation. This was dangerous territory for Mr Clarke, as it would be for any American. Dr Rice is the highest-ranking woman and the highest-ranking black official in the US. She has enjoyed a glowing press for most of her life; since her name was first mooted as a possible member of Mr Bush's campaign team four years ago, she has been untouchable.
As Dr Rice well understood, however, the territory was, if anything, more dangerous for her. An ultra-discreet individual who does not place herself gratuitously in the public eye, she took to the airwaves last weekend to defend herself, appearing on every television talk show in sight to insist that she had nothing to hide. She had unusually waspish words for her accuser, too. Rebutting his charge that she appeared not to know anything about al-Qa'ida, she said: "I find it peculiar that Dick Clarke is sitting there reading my body language. I didn't know he was good at that, too." For a moment, Dr Rice's ultra-cool demeanour seemed to have left her. We can perhaps look forward to more of this robust bitchiness on Thursday. But the woman now known the world over as Condi will have to be very careful.
Throughout her career, Dr Rice has cultivated an image of extreme diligence, bordering on perfectionism, which she combines with an air of sometimes infuriating self-belief. She rarely allows the personal to intrude on the professional. She keeps out of the gossip columns and seems to have no private life at all, unless you count the weekends that she spends with the Bush family - fishing and sailing off the coast of Maine, at Camp David, or at the Bush family ranch in Texas. Now 49, she lives alone in a flat that she bought soon after her appointment as National Security Adviser in the exclusive Watergate development. She is occasionally spotted dining in one of the restaurants there with Madeleine Albright or other colleagues from the political or academic élite.
The path that took Condoleezza Rice to the White House from her childhood in Birmingham, Alabama, in the segregated south is the stuff of American legend. Ambitious parents invested all their own hopes in her. She started piano lessons at three and gave her first recital at four. Something of a child prodigy, she reached close to concert soloist standard before concluding that she was no Mozart - she would have to "practise and practise and still wouldn't be extraordinary" - and ditching the idea of a professional career. As well as school lessons, she attended French and Spanish classes, and rose before dawn to practise her ice-skating at the rink.
Not everywhere was so tranquil. Outside their relatively prosperous suburb, racist violence cost the life of one of her kindergarten friends when a church was fire-bombed. When she was 11, her parents moved first to the quieter town of Tuscaloosa, and then to Denver. She has hinted that it was initially harder for her at school in the whiteness and spaciousness of Denver than in the black schools of the south. Still, she completed school two years early and went on to the local university. Rather than study music, as she had intended, she transferred to politics and Russian. By coincidence, her tutor and inspiration there was Josef Korbel, the father of Madeleine Albright.
Condoleezza returned to Denver for her doctorate - on relations between the Soviet and Czech military - before being snapped up for a lectureship at Stanford, the prestigious private university in California where she has spent her entire academic career. Stanford was then the powerhouse of Soviet and related studies, and Dr Rice distinguished herself with awards for her teaching and research. She was later to return as provost, the top administrator, and bring the then cash-strapped institution back to solvency.
Dr Rice's Washington career began almost by chance in 1988, when she caught the attention of the then national security adviser, Brent Scowcroft, at a seminar. He professed amazement that such a "slip of a girl" had asked so perspicacious a question. The following year, when George Bush became president, he invited her to join the National Security Council. As the main adviser on policy towards the Eastern Bloc, she helped to steer the administration's non-interventionist policy through one of the greatest geo-political shifts of the 20th century.
After only two years, however, she returned to Stanford, citing a desire for more "balance" in her life, after the all-consuming agenda in Washington. She later dismissed reports that she had returned to "seek a husband and start a family". If that was the reason, it did not happen.
She was never enamoured of Washington, but her friendship with the Bush family endured. And when George W Bush quizzed her about foreign policy during visits to Maine and Texas, they developed a rapport. He praised her for setting out complex policy issues in ways he could understand. The trust he invested in her gave her considerable authority when he recruited her to his campaign team in 2000 and then, after he was elected, as his National Security Adviser.
As a supremely well-qualified black woman in the front line of a Republican campaign that was preaching "compassionate conservatism" and social inclusiveness, she was a huge asset. And in her convention speech - one of her first political speeches - she gave a rare glimpse of how far she and her family had come. "Grandaddy Rice", she said, was a poor farmer's son in the cotton fields, who had enquired how he could get an education. He took a scholarship conditional upon becoming a Presbyterian minister.
But she also outlined the philosophy of self-improvement and self-reliance that had driven her to achieve and, after a brief flirtation with the Democrats, led her to become a Republican. "I found a party," she said, "that sees me as an individual, not as part of a group... In America, with education and hard work, it really does not matter where you come from - it matters where you are going."
All this is what she calls her "American story". But there is another aspect of Dr Rice's biography that is not mentioned. Aged 10, when the US passed its landmark desegregation laws, at college during the dawn of the women's movement, she was of an age to ride the crest of every social wave. Her decision to specialise in Russia and the Soviet Union was inspired. She was a woman and black and a Soviet specialist at a time when all were in demand. Before becoming National Security Adviser, she had acquired a string of directorships, including the oil company Chevron, and was well on the way to becoming a wealthy woman.
A closer look at her CV, however, raises questions. As an undergraduate, she fell short of the very top grade at a non-Ivy League university. Her first book (of her thesis) received neutral to withering reviews, in terms that suggested she was unable to sift facts from propaganda. Her subsequent, better-reviewed books have all been co-authored. As provost of Stanford, she was criticised for her abrupt management style and for not supporting "affirmative action" for minorities, even though she had benefited from the policy herself.
When she was tipped for the NSC, a few tentative voices asked whether her narrow specialisation in a country and a system that no longer existed was the best preparation for her new role. And while she is always praised as a "quick study" with an admirable grasp of detail, you will not hear words such as vision, perspicacity or flair.
All these are the reasons why Dr Rice is suddenly vulnerable - and with her, the President who so trusts her. Richard Clarke's essential criticism - that she was not up to the job - hit home because it exposed weaknesses that have lain just beneath the surface of a dazzling career. She presents the case for her defence on Thursday.
A life in brief
Born: 14 November 1954, in Birmingham, Alabama to the Rev John Rice, a Presbyterian pastor and college principal, and Angelena Rice, née Ray, teacher.
Family: Single, no children.
Education: University of Denver, BA in political science (1974); University of Notre Dame, MA (1975); University of Denver, PhD in international studies (1981).
Career: Lecturer, Stanford University (1981-1993); seconded to National Security Council (1989-91); Provost, Stanford University (1993-99); National Security Adviser (2001- ).
Interests: Concert-standard pianist, opera lover, American football and baseball enthusiast.
She says...: "When the Founding Fathers said 'we the people', they did not mean me. My ancestors were three-fifths of a man."
They say...: "Condi was raised first and foremost to be a lady." - Colin Powell
"If you look behind her, the ground is littered with the bodies of those who underestimated her." - Richard Armitage, Deputy Secretary of State