Eurovision 2015 semi-final one: Five acts to watch - from Russia and Estonia to the Finland punk band with learning disabilities

Who should you keep your eyes on ahead of Saturday's final?

(Stina Kase)

While the UK's Eurovision entry this year is not one of the favourites, at least - owing to Britain's economic clout in Europe - it doesn't have to compete for a place in the final like other nations have to.

Britain, France, Germany, Italy and Spain are the "Big Five", the main sponsoring nations who always make the final of the contest. They will be joined in the final by Austria, the reigning champions, and Australia, the competition's wild card, invited to take part to commemorate the 60th anniversary of Eurovision.

The rest of the hopeful nations have to take part in semi-finals, with one taking place on Tuesday and the second on Thursday. These events will whittle down 33 countries to 20.

The decision of who gets to go through is decided by TV viewers at home and professional juries from all the countries competing in each of the semi-finals. On Tuesday's semi-final, the votes from the viewers and juries of Spain, Austria, France and Australia will also go towards the semi-final decision.

With two of this year's favourites already in the final (Italy and Australia) are there any acts to watch out for on Tuesday who might go on to snatch a surprise win?

Estonia: Elina Born & Stig Rästa, "Goodbye To Yesterday"

Estonia has steadily been rising up the betting odds, currently standing at 11/1 favourites to find glory in Vienna. Male and female duets have only won the competition two times before, but Elina Born and Stig Rästa are gaining some late momentum with their song, "Goodbye To Yesterday".

Stig Rästa may be unknown to most Brits, but he is responsible for managing and writing music for Estonia's Pop Idol finalists. Rästa discovered Elina Born on YouTube, and the Eurovision bloggers are raving about her powerful performance in the semi-final rehearsals.

Russia: Polina Gagarina, "A Million Voices"

Russia, winners in 2008, look set to have another good year, with the country choosing an established singer in Polina Gagarina, who is currently working on her third album. Eurovision commentators write that Gagarina's song ticks all the right boxes and has performed the tune incredibly well in the rehearsals.

With the bookies placing her chances of winning at 9/1, she has a chance: Daniel Gould, a Eurovision expert on sofabet.com, writes of her, "Polina has no problem belting it out when it matters."

Finland: Pertti Kurikan Nimipäivät, "Aina Mun Pitää"

The odds of this Finnish punk rock band have lengthened in recent days, but esctoday.com reports that their rehearsals have been well received by press and fans alike in Vienna's Wiener Stadthalle.

The band was formed in a charity workshop for adults with developmental disabilities, and will hope their rock act will triumph like compatriots Lordi, who won in 2006.

Georgia: Nina Sublatti, "Warrior"

Georgia's Nina Sublatti has some striking staging in her rendition of "Warrior," although she has fallen ill in recent days and this has affected her performances. Still, the country has a good record in proceeding through from the semi-finals.

It will be interesting to see whether Sublatti can recover in time for tonight to ensure she delivers a strong showing to make it through to Saturday. She currently stands at 100/1 to win the contest outright.

Romania: Voltaj, "De La Capat/ All Over Again"

Another dark horse in the contest, although a popular band in Romania, having been on the circuit for the last two decades. Having toured around the likes of Moldova, Austria, Italy, Spain and Ireland, they may pick up some decent points from fans in those countries.

Entertainmentodds.com gave the band a great review during the rehearsals, describing it as a "very evocative set...and flawless vocal as usual."