Ghana's Peter Turkson is the the bookmakers' favourite to replace Pope Benedict.
If Turkson is elected, it'd put a non-European in pole position to lead the 1.2 billion-member Roman Catholic Church for the first time in more than a millennium.
Bookmaker Paddy Power offered odds of 11/4 against for Turkson, meanwhile while Ladbrokes offered odds of 5/2 against.
Turkson would be the first non-European to lead the Catholic church in more than a millennium if he is chosen to succeed Benedict. Italian Angelo Scola is second favourite according to Paddy Power at 3/1 against.
The new pope will inherit a Church scarred by Vatileaks and by child abuse scandals in Europe and the United States, both of which may have weighed on Benedict's decision to decide he was too old and weak to continue the papacy.
The pope has two days left before he takes the historic step of becoming the first pontiff in some six centuries to step down instead of ruling for life.
Betting on the new pope earlier in February had ranked Nigeria's Cardinal Francis Arinze and Canadian Marc Ouellet alongside Turkson in a three 'cardinal' race.
Some 115 cardinals will enter a closed-door conclave at the Vatican in March.
Paddy Power said Turkson has attracted the highest number of bets, accounting for 15 percent of the market and is shouldering the biggest single bet of 5,000 pounds ($7,600).
The head of the Vatican's justice and peace department, the Ghanaian has been tipped as Africa's frontrunner in a contest heavy with speculation that a Latin American or African could be elected as chief of the 1.2 billion-strong Catholic population.
While Canada's Ouellet is still in the running at 7/1 according to Ladbrokes, Arinze's standing at both bookmakers has sunk to 25/1.
Paddy Power said that betting on who will be elected as the new pope is set to become the largest non-sporting market in its history. It said it had taken 300,000 pounds on "pope betting".
Dark horses include a fictional character from Irish sitcom Father Ted, the simple-minded Father Dougal McGuire, who has attracted nine more bets than real-life Brazilian Cardinal Claudio Hummes.