Spain’s Izagirre and American McNulty formed part of a six-rider move in the closing kilometres of the 189.2km fourth stage from Gasteiz to Hondarribia.

The pair were joined by Spain’s Pello Bilbao, Denmark’s Jonas Vingegaard, Germany’s Emanuel Buchmann and Colombia’s Esteban Chaves.

The six riders attacked on the descent after the final climb of the day at Erlaitz, with a little less than 20km to go.

The general classification group failed to organise quickly, which enabled the group to build a lead and remain clear to the finish.

Buchmann and Chaves attempted to secure the stage win with solo attacks in the final stretches, but were unable to pull clear.

Izagirre clinched the stage win after the Astana-Premier Tech rider held off the challenge of Bilbao to cross the line in 4 hours 17min 7sec.

Bilbao was left settling for second place, with McNulty completing the top three on the stage on the same time as the winner.

Third place gave McNulty a four-second time bonus.

The UAE Team Emirates rider had been 30 seconds behind race leader Primož Roglič of Slovenia at the start of the stage.

McNulty now leads the race by 23 seconds, with Roglič dropping to second.

Vingegaard and Bilbao climbed into the top four in the standings, with the duo 28 and 36 seconds behind the new race leader.

The penultimate stage of the race will take place tomorrow, with riders tackling a 160km route from Hondarribia to Ondarroa.