The Slovakian completed the stage in 4 hours 28min 38sec for a first triumph in nine months.

The 32-year-old, who has suffered from COVID-19 and other illnesses in recent months, last won at the 2021 Giro d'Italia.

Sagan never looked back once he moved into a key position with just a kilometre left in the 177km route from Aesch to Grenchen.

France's Bryan Coquard, who rides for Cofidis, managed to cross the line second.

Norway’s Alexander Kristoff, an Intermarché-Wanty-Gobert cyclist, followed in third.

Bahrain Victorious rider Stephen Williams of Britain remains the overall leader following his initial victory on the first stage of the race.

Williams leads Andreas Kron, a Dane in Lotto Soudal colours, by six seconds.

Both were given the same time as the stage winner today. 

"I told you already it’s hard to get back in a racing mood after my sickness and three months without racing - it just needs time," Sagan said at the finish.

"It's just a stage win, I’m happy for that and for the team, they did a great job on the front pulling all day. 

"In the end I made it, and I’m just happy for that."

Stage four is scheduled to take place tomorrow as riders tackle a 191km route from Grenchen to Brunnen.