The average odds by seven of the largest bookmakers gave Serbia the top position with 8-1 odds followed by Sweden with 9-1 odds and Belarus with 10-1.
Britain's main bookmaker Ladbrokes was offering odds of 5-1 on Sweden, 6-1 on Serbia and 7-1 on Belarus.
Out of the three favourites only Sweden, represented by glam-rockers The Ark, has secured a place in the final on Saturday after finishing in the Top 10 last year. Serbia and Belarus will have to qualify at the semi-final on Thursday.
Fred Bronson, a journalist for US weekly music magazine Billboard, said he also believed Serbia had a good chance to win, but mentioned Switzerland and Andorra as other favourites.
"Serbia is very strong this year, but Andorra is coming fast," Bronson told AFP.
Serbia's entry is entitled "Molitva", a love song about the uncertainties between God and man, performed by 23-year old Marija Serifovic.
Bronson was pleased with the line-up this year.
"We have a good quality and very different styles, new age, pop and even swing with the German band," he said.
Other entries that are expected to place highly are Russia, Ukraine, Bulgaria, Greece and Cyprus.
Finnish monster rock group Lordi won the competition last year and host country Finland is again listed among the Top 10 favourites, this time with the more glamorous artist Hanna Pakarinen.
The "big four", the founding countries and largest financial contributors Germany, Spain, France and Britain, are however not rated high on bookmakers lists.
A record 42 countries are to take part in the 52nd Eurovision Song Contest in Helsinki on Saturday.