The Briton finished third on-the-road in a tense penultimate round which would have been enough for the title, but the result was guranteed when he was promoted to second after Antonio Felix da Costa was handed a three-minute penalty for a technical infringement after finishing second.
Dennis’ closest championship rival Cassidy had led early in the race from pole, but his championship chances were dashed after Envision Racing team-mate Sebastien Buemi damaged his front wing.
Cassidy made the perfect start from pole while Dennis was forced to defend from Buemi into the opening turns, but he had to give best to the Envision driver on the exit of Turn 4.
Buemi initially proceeded to act as rear-gunner to Cassidy and began to back the pack up with Cassidy able to take both Attack Mode activations inside the first seven laps and rejoin in the lead both times.
But things began to unravel for the championship protagonist when he let Buemi ahead into T16, a move which would allow his team-mate to take his own Attack Mode activations and lose less time and positions.
Evans – who had risen to third from sixth on the grid having taken pole before serving his five-place grid penalty for colliding with Cassidy in Rome – also took the opportunity to move ahead of Cassidy into the left-hand Turn 17.
It meant that when Buemi activated his first Attack Mode the next lap he rejoined in front of Cassidy, whose attentions turned to Dennis behind him.
Source: Autosport