The 172 kilometres route from Avola to Etna Nicolosi was the first stage of this year's Giro being held in Italy after the first three days of racing took place in Hungary, and featured a challenging 22.8km ascent at an average gradient of 5.9 per cent as its finale.

Kämna and López broke away and made it a two-way battle in the closing minutes.

It was the Bora-Hansgrohe rider Kämna who came out on top, clocking 4 hours 32min 11sec to secure his second Grand Tour stage victory.

López of Trek-Segafredo was left frustrated with a mistake on the final bend, with a misjudgement leading to him finishing one second behind Kämna.

However, López did claim the pink jersey from Dutchman and Alpecin-Fenix Giro debutant Mathieu van der Poel.

Estonia's Rein Taaramäe of Intermarché-Wanty-Gobert Matériaux was 34sec off the pace in third place.

The peloton was led by Belgium and Lotto-Soudal's Sylvain Moniquet, who came through in fourth with a time of 4:34:23, with compatriot Mauri Vansevenant of Quick-Step Alpha Vinyl completing the top five.

The 2019 Giro winner Richard Carapaz of Ecuador, racing for Ineos Grenadiers, placed seventh in the fourth stage.

López holds a 39sec lead over Kämna at the top of the general classification, with Taaramäe completing the top three 58 adrift.

Britain's Simon Yates, third last year, of Team BikeExchange-Jayco, is fourth and trails López by 1min 42sec, with Vansevenant 5sec further back in fifth.

The fifth of the 21 stages is due to be held tomorrow on a 174km flat route from Catania to Messina.