The Italian attacked from a 13-man breakaway to solo to victory and into the leader's jersey as Dumoulin suffered on the day's main climb
Gianluca Brambilla (Etixx-Quick Step) capitalised on his strong position in GC to take the pink jersey along with stage victory on the eighth day at the Giro d’Italia, attacking from the breakaway to take his maiden Grand Tour stage victory.
It was a bad day for race leader Tom Dumoulin (Giant-Alpecin) though, who was dropped by his GC rivals on the category two climb of Alpe di Poti and slipped out of the top-10 overall.
Italian Brambilla sat at 1-56 at the start of the day, but was able to find himself in the large 13-man breakaway group which managed to establish a five minute gap on the bunch behind.
And the chase in earnest never really got going in the main group, with Giant-Alpecin forced to do much of the work, and the break still carried over four minutes within the final 40km.
The key moment of the day was always going to be the Alpe di Poti and its dirt roads within the final 25km of the 186km route, and the break quickly fell apart as the likes of Matteo Montaguti (Ag2r La Mondiale) and Brambilla attacked.
The 28-year-old Etixx rider was able to rapidly put a decent gap between him and his breakaway companions and managed to hold Montaguti at around 45 seconds behind with the GC contenders almost two minutes back, as he made a daring and fast descent from the summit of the climb.
As Brambilla powered on, Alejandro Valverde (Movistar) was causing fractures in the group behind as he attacked on the early slopes of the climb with around 23.9km to go, with all the GC hopefuls, including Vincenzo Nibali (Astana), Esteban Chaves (Orica-GreenEdge) and Mikel Landa (Sky) all able to stick with the Spanish champion.
But there was no such luck for the pink jersey Dumoulin, as he was quickly dropped and struggled to make any gains into the minute he quickly lost on the Valverde group.
As Brambilla soloed to victory in Arezzo, the GC contenders rolled in 1-41 behind, with a slight split of three seconds to a group containing Nibali, Rafal Majka (Tinkoff) and Rigoberto Uran (Cannondale) in the sprint for the finish. But Dumoulin could only minimise his losses to around 1-10, slipping to 11th overall.
With the long time trial on Sunday, there’s still a strong chance for the Dutchman to retake the pink jersey and overhaul the 1-05 gap to Brambilla at the top of the standings. But he’ll have to wary of the likes of Ilnur Zakarin (Katusha) who sits at 23 seconds in second place and is an able rider against the clock and will certainly have his eyes on pink.
Sunday’s stage nine sees the riders take on the rolling 40.5km Chianti time trial that could have a big impact on the overall classification of this Giro d’Italia, with a welcome rest day on Monday as the race heads towards its second week.
Giro d’Italia 2016 stage eight, Foligno – Arezzo (186km)
1. Gianluca Brambilla (Ita) Etixx-Quick Step, in 4-14-05
2. Matteo Montaguti (Ita) Ag2r La Mondiale, at 1-06
3. Moreno Moser (Ita) Cannondale, at 1-27
4. Jaco Venter (RSA) Dimension Data, at 1-28
5. Alessandro De Marchi (Ita) BMC, at 1-33
6. Alejandro Valverde (Esp) Movistar, at 1-41
7. Steven Kruijswijk (Ned) LottoNL-Jumbo
8. Mikel Landa (Esp) Team Sky
9. Esteban Chaves (Col) Orica-GreenEdge
10. Ilnur Zakarin (Rus) Katusha, all same time
Overall classification after stage eight
1. Gianluca Brambilla (Ita) Etixx-Quick Step, in 33-39-14
2. Ilnur Zakarin (Rus) Katusha, at 23s
3. Steven Kruijswijk (Ned) LottoNL-Jumbo, at 33s
4. Alejandro Valverde (Esp) Movistar, at 36s
5. Vincenzo Nibali (Ita) Astana, at 45s
6. Esteban Chaves (Col) Orica-GreenEdge, at 48s
7. Rigoberto Uran (Col) Cannondale, at 49s
8. Rafal Majka (Pol) Tinkoff, at 54
9. Domenico Pozzovivo (Ita) Ag2r La Mondiale, st
10. Mikel Landa (Esp) Team Sky, at 1-03
11. Tom Dumoulin (Ned) Giant-Alpecin, at 1-05