Roman Catholic cardinals began a secret Papal election in the Renaissance splendour of the Sistine Chapel yesterday but their first vote failed to find a successor to Pope John Paul II.
Some two-and-a-half hours after the cardinals locked themselves away from the world inside the frescoed chapel, thick black smoke billowed out of the chamber's chimney, indicating that no candidate had won the required two thirds of votes.
Before the clear signal emerged there were moments of confusion as faint wisps of grey smoke puffed out, causing some of the thousands of people waiting in St Peter's Square to cheer in the belief a Pope had been elected in record time.
At least one Italian news organisation also reported white smoke - the signal for a conclusive vote.
Similar confusion occurred in two 1978 conclaves and the Vatican had installed a new furnace to try to avoid a repeat.
Before the 115 cardinal electors from 52 countries locked themselves in the chapel for the conclave, top conservative candidate Joseph Ratzinger urged them to choose a Pope who would protect the strict orthodoxy of John Paul.
The pre-conclave sermon by Cardinal Ratzinger, John Paul's doctrinal watchdog for 23 years, was seen by many Vatican observers as a transparent attempt to promote the German's own candidacy.
Whoever eventually emerges as leader of the 1.1 billion Roman Catholics will not only have to fill the vacuum left by one of history's most dynamic Popes but face a host of dangerous challenges, including the divided Church he left behind.
Accompanied by a choir chanting Latin prayers, the red-robed "princes of the Church" walked in procession into the Sistine Chapel, where Michelangelo's fresco of the Last Judgment will stare down on their deliberations.
One by one, the cardinals placed their right hand on a book of the gospels laid in the middle of the chapel, swearing an oath of secrecy and fidelity to the Church.
At a Mass hours before the conclave opened, Cardinal Ratzinger warned the cardinal electors that they must stick to traditional teachings and shun pressure to follow modern fads.
"An adult faith is not one that follows tides of trends and the latest novelties," he said.
Since John Paul's death on April 2, media and bookmakers have tipped Cardinal Ratzinger, a close aide of the Polish Pontiff and preacher at his funeral, as the early favourite to succeed him.
But most Vatican experts doubt the 78-year-old German will be able to garner the majority needed.
Following the opening oath, Archbishop Piero Marini, the master of Papal ceremonies, said in Latin, "Extra omnes" - "Everyone out" - ordering non-electors to leave the room.
The cardinals sat side-by-side on two sets of double-rowed tables that stretched down the chapel. Each had a name plate, underscoring the fact that many of them do not know the others very well.
This factor also strengthens the role of influential "kingmakers" who can lobby undecided cardinals.
As the wooden doors of the Sistine Chapel closed, applause broke out on St Peter's Square where crowds of faithful had followed the opening ceremony on giant television screens.
"If you don't believe, you think this is like politics. But if you believe, as I do, in the power of prayer, you know they will be illuminated to make the right choice," said Annick Vandamme, who had travelled from Paris.
Under the terms of centuries-old Church law, the cardinals will vote up to four times a day from today, twice in the morning and twice in the afternoon, until a Pope is selected.
Of the eight 20th century conclaves, none took longer than five days, and two were completed on the second day.
Most Vatican experts expect a relatively quick conclave this time around, predicting that white smoke will rise above the Sistine Chapel tomorrow evening or Thursday.
They fear a long conclave would point to deep and dangerous divisions.
Among the major issues facing the next Pope are the growing spiritual poverty of Europe, the material poverty of the Third World and devolution of power within the Church.
Critics of John Paul said he focused too much power in the hands of the Vatican and smothered theological debate.
Cardinal Ratzinger urged the need for doctrinal purity but made no mention of concerns other cardinals have expressed such as poverty and justice, Islam, bioethics, sexual morality, Church reform or the role of women in Catholicism.
As in mediaeval times, the cardinals will be banned from communicating with the outside world, but the Vatican has taken new high-tech measures to ensure secrecy in the 21st century.
Mobile phones, newspapers, television, radio and the internet will be banned. A false floor has been built in the chapel to accommodate electronic counter-bugging measures.
The cardinals will hold no debate within the Sistine Chapel but will be able to hold informal chats over meals and in their sequestered lodgings, which lie within the walled Vatican City.
In a last burst of speculation, Italian newspapers said the opening tussle would pit Cardinal Ratzinger against a progressive such as Italy's Carlo Maria Martini to test the strength of rival camps.
But in conclaves, like long-distance races, it is considered a disadvantage to break from the pack too early.