Who will be the next pope? Cardinals who elect Benedict XVI's successor after his resignation later this month must choose a leader capable of guiding the church through a difficult period, marred by scandals, internal tensions and growing secularism.
Benedict's rule has been criticised as overly "eurocentric" in some quarters and Vatican watchers say the college of cardinals set to meet in the Sistine Chapel in the Vatican for the secret vote may seize the moment to elect a Latin-American, African or Asian pope.
Others say 85-year-old Benedict - who is resigning for age reasons - may call on the cardinals to elect someone younger, who is less likely to suffer failing health early in his mandate.
"His decision to step down will have a big influence on the choice of the future pope. The old must make way for the young. The church needs it," said Marco Politi, Vatican expert and author of a celebrated biography on Benedict.
While bookmakers had given even odds on the choice of Joseph Ratzinger in April 2005, no-one had foreseen Karol Wojtyla's surprise election in 1978.
There are 118 cardinals who are under the age of 80 and therefore eligible to vote in Benedict's successor. The red-robed cardinals, who usually meet between 15 and 20 days after the death of a pope, take an oath of secrecy when they enter -- and are automatically excommunicated if they break that oath.
Of those voting, 67 were selected to be cardinals by Benedict - known for his staunch conservatism - while the 51 others were picked by John Paul II, who was seen as even more conservative.
Sixty-two of the cardinals are European, 28 of whom are Italian, while 19 come from South America, 14 from North America, 11 from Africa and 11 from Asia and one from Oceania.
Among those tipped as possible candidates for St Peter's chair are Canadian Marc Ouellet and the Archbishop of Milan, Angelo Scola, though some analysts have said they are likely to be considered as not charismatic enough to revive faith amid rising secularism.
Previous hot tickets Peter Erdo, from Hungary, and the pope's Austrian friend Christoph Schoenborn, have recently dropped in favour, while American Timothy Dolan is increasingly tipped for his mediatic skills -- key in helping the Vatican overhaul its image in modern society following a damaging wave of clerical child abuse scandals.
While a quarter of the cardinals who can elect a new pope are Italian, watchers say their chances of a win this time were scuppered by the leaks scandal which hit the Vatican last year, which was blamed by some on internal bickering between Italians jostling for power.
Among the potential candidates for the first African pope are Peter Turkson of Ghana -- the head of the Pontifical Council for Justice and Peace who is considered a progressive candidate -- and Nigerian John Onaiyekan.
William Hill bookmakers in London on Monday tipped 80-year-old Francis Arinze of Nigeria as their favourite to take over from Benedict, with odds of 2-1, followed by Turkson at 5-2.
Frontrunners in Latin America - which boasts the largest number of practicing Catholics in the world - are Claudio Hummes and Joao Braz de Aviz.
Progressives favour Honduran Oscar Rodriguez Maradiaga, head of Caritas Internationalis, but he is considered by the Church's more traditional members to lean too far left, and is unlikely to win the two-thirds majority needed.
Among the outsiders to watch, experts note dynamic Manila Archbishop Luis Antonio Tagle - the Church's second youngest cardinal, appointed just last year at 55 years old - is very popular in Asia and is rising fast within the Vatican.