Oss swept all three KOMs (Cat. 4) before Mount Hamilton. Midway through the stage, the gap to the escapees was hovering around 3:15 with the big mountain (HC) still to come. At the foot of the ascent of the behemoth, Toms Skujiņš accelerated away from his companions. Soon the gap grew and he was first at the KOM point, amassing 12 points. The peloton exploded as they tackled Mount Hamilton. The riders then negotiated the twisty descent on good tarmac. After the difficulty of the day, Peter Sagan suffered a mechanical incident but reintegrated the pack on a small non-categorized rise. The next KOM came shortly after the descent and was named Quimby (Cat. 2). Skujiņš won this KOM too and fell off his machine in a tight bend on the descent as he made contact with a protective haystack, but remounted straight away. With to cover, he still enjoyed an advantage of 2:30 on lone pursuer Oss and 4:00 over the reduced peloton.