- McNulty snatches the lead from Roglic
- Pello Bilbao takes fourth place
In the fourth stage, the peloton set off at a blistering pace which averaged nearly 50 km/h during the first two hours. The first 100 km saw several breakaway attempts by the riders, but the gap to the peloton was only about 10 seconds.
It wasn’t until km 102 that Guillaume Martin (95, COF), Ben O’Connor (154, ACT), Jefferson Cepeda (197, CJR) and Juan Pedro Lopez (97, TFS) were able to break away from the peloton with a lead of almost 3 minutes. But Martin and Cepeda dropped back during the climb to Jaizkibel.
The peloton, which continued at a high pace, fought back and with 30 kilometres to go, the gap was reduced to 30 seconds. Just before the climb to Erlaitz, the peloton was back together, and both Brandon McNulty (33, UAE) and Mikel Landa (171, TBV) tried to break away as the climb began but were ultimately caught by the peloton before reaching the summit.
The lead group began to break away containing several favourites: McNulty, Esteban Chaves (21, BEX), Ion Izaguirre (1, APT), Pello Bilbao (173, TBV) Jonas Vingegaard (147, TJV) and Emmanuel Buchmann (13, BOH). Entering Hondarribi, the six riders began to push hard and in the final sprint Izaguirre took the stage in a photo finish.