Geneva police had to break up fights outside a polling station set up for Brazilians on Sunday.
Some supporters of the two candidates came to blows.
Although there were no arrests, witnesses say the atmosphere was tense.
The result from the Geneva poll showed the race was virtually neck and neck.
The contender, Lula da Silva beat the incumbent Jair Bolsonaro by just 52 votes out of a total of nearly 4,000 cast.
Heat to stay for now
The heatwave alert has been extended until Thursday, with temperatures set to climb as high as 37 degrees in some areas.
Growing anger over World Cup red card
The Swiss team's manager, Murat Yakin has called Breel Embolo's red card 'unacceptable', as anger builds over the refereeing of Switzerland's World Cup quarter-final loss to Argentina.
Fire damages trees in the Jardin Anglais
A fire tore through part of Geneva's Jardin Anglais on Saturday morning, gutting several trees and damaging a lakeside building used by the Mouettes ferry service.
Cows sweltering in the heat
The heat is now hitting the country's dairy herds, with cows producing less milk as they burn extra energy to stay cool.
Lake Geneva nudists fight for their lake section
A hidden stretch of Lake Geneva shoreline has become the focus of a long-running battle over public nudity.
Holiday makers seek more than the sun
Nearly half of Swiss holidaymakers are choosing to learn a new skill on their summer break rather than simply lie on a beach.
