- Lucas di Grassi takes Formula E title
- A win and seventh place in Montreal
- Disastrous weekend for Sebastien Buemi
Audi Sport's di Grassi finished seventh in the second of two races in the Canadian City, enough to secure the title ahead of a Buemi, who could only manage 11th.
France's Jean-Eric Vergne took the victory, the first in Formula E for his Techeetah team, with Sweden's Felix Rosenqvist (Mahindra Racing) in second place to claim third in the overall standings.
Di Grassi, who had finished third in the inaugural Formula E season and second last year, was in tears as he crossed the line, having reached the top step of the podium at last.
Buemi had gone into the Montreal rounds with a 10-point advantage over di Grassi, having won six races out of 10 in a dominant season, but a heavy crash in the second practice session was the first of a series of devastating setbacks.
Starting from 12th on the grid in his Renault e.dams car, Buemi fought his way through to finish fourth behind Di Grassi, who took victory and 28 points after claiming pole.
On his way through the field, Buemi clashed with di Grassi's teammate Daniel Abt and he was involved in a heated and very public altercation with the German in the pit lane after race one.
But worse was to follow for the 2016 champion when race officials discovered that the car he had used was underweight, leading to disqualification and leaving his title hopes in tatters.
Di Grassi, pipped to the title by Buemi in controversial circumstances last season
, went into the second race Sunday with an 18-point buffer and could afford to cut out any risks with his rival behind him on the grid after another lackluster qualifying performance.
Buemi's chances of overhauling him were further damaged when Antonio Felix da Costa clipped him from behind on the first corner to leave him at the back of the field.
By the finish di Grassi he had extended his advantage to 24 points, but consolation for Buemi's team was a third straight victory in the constructors' category.
"After two close seasons we finally made it," di Grassi said at the prize presentations. "I'm so proud of my team and myself," he said.