Sobral came into the competition having told local media that he has a heart problem, without giving details. In the run-up he wore a sweatshirt drawing attention to the migrant crisis in Europe, but was asked to stop wearing it by the organizers.
"I hope this can bring a change not only to this contest, but to music in general, and pop music," Sobral said about his win, contrasting his song to music normally pumped out "16 times a day" on radio stations.
Other hopefuls this year included Italian Francesco Gabbani. He was tipped to win with a number, viewed nearly 114 million times on YouTube, that mixes Buddhist imagery with a dancing ape, and that he explained as poking fun at the West's superficial embrace of eastern culture.
Jacques Houdek, known as 'Mr Voice' in Croatia, blended pop and operatic singing styles in the song "My Friend". Romania fielded a duo that combined rap and yodelling.
Ukraine has won the competition twice, including last year with a song about the mass deportation of Tatars from Crimea by Josef Stalin, and its winners performed on Saturday.
Moscow fielded a candidate this year who had violated Ukrainian law by performing in Crimea after the Russian takeover. Kiev accused Moscow of deliberately provoking a row.
Russian singer Yulia Samoylova performed in Crimea again on Tuesday, coinciding with the first Eurovision semi-final. (Full Story)
"I think politics shouldn't intervene," said Liza Ignatieva, a 21-year-old university student in Moscow. "But they broke the rules of the event by not letting her in. Why they invented new rules for Russia only? Yes, we have bad relations but they shouldn't do it to us."
More than 10,000 have been killed in the war between Ukraine and pro-Russian fighters that erupted in 2014 following the Maidan street protests that ousted a pro-Russian president, and the annexation of Crimea.
But during Eurovision at least, Maidan and its surrounding streets have been filled with fans. Big screens and food stalls have been set up in the centre of the capital, and Ukrainian memorabilia put on sale.
"And yes, there is a war going on, but it's further, further out," said Stephanie Novak, a visiting fan from Australia.
"And I think isn't it the whole point of Eurovision to help bring Europe together? What could be better than bringing Europe to a country that is being so affected by war at the moment and to show them what a beautiful country it is."
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