Buemi was furious after the race, firstly with Sarrazin after a robust defence from the Frenchman on the 35th and final lap and then with both Antonio Felix da Costa and Andretti team-mate Robin Frijins.
On the first lap, Frijins dived up the inside at Turn 2, and broke Buemi's suspension, causing his steering wheel to be leaning to the right, after Buemi had dropped to P16 from his P12 grid slot.
The Swiss driver then began to battle through the field, passing the mid-field runners before coming up against title rival Di Grassi's team-mate Daniel Abt.
On lap 10, a full course-yellow was deployed for Nick Heidfeld's damaged Mahindra after an attempt at a move on Loic Duval at Turn 6 went wrong and he abandoned the car in the final chicane.
As the entire field, except Adam Carroll and Jerome D'Ambrosio pitted, Abt drove slowly down the pit-lane, to try and hold Buemi up.
Buemi's E.Dams garage was located at the end of the pit-lane and as the minimum pit-stop time of 57s elapsed, he was waved away, just ahead of Abt.
The German then rammed the rear of the E.Dams as Buemi slowed to get to full-course yellow speed, and the incident was noted by the stewards.
He was in ninth after the stop, having been around 18 seconds behind leader Di Grassi.
Meanwhile up front Di Grassi was relatively untroubled throughout the first part of the race, enjoying a comfortable buffer of around 4s to the chasing pack, using only slightly more energy in the process.
Lopez safety car bunches the field
Buemi was quickly into his stride in his hastily built second car, after he wrote off the old one in a heavy practice crash, and despatched both a struggling Mitch Evans, and Oliver Turvey for sixth, with team-mate Nico Prost in fifth.
However, on lao 25, Buemi's Toyota WEC team-mate Jose Maria Lopez got a snap of oversteer on the exit of Turn 6 and smashed into the wall, bringing out a safety car.
The safety car remained out until the end of lap 27, creating an eight lap sprint for the finish, with the order being Di Grassi, Vergne, Sarrazin, Felix Rosenqvist, Prost, Buemi and Abt.
On the restart, the two leaders escaped up the road, as Buemi was just about waved through by Prost to aid his title challenge at Turn 2.
Rosenqvist, giving pressure to Sarrazin, hit the wall on the exit of Turn 14 and immediately slowed with damage to the left-rear of the Mahindra, falling back to evantually finish in 10th place.
Abt, along with Buemi was easily able to pass the stricken Rosenqvist while Prost had more trouble doing so, losing Buemi his rear-gunner.
The championship leader was able to reel in Sarrazin, and on the final lap in the 90 degree section of the track around Turn's 6/7/8 the two went side-by-side with Sarrazin just about coming out ahead.
Despite Vergne looking to make the move for the lead, which would have been his first in FE, he failed to offer one, and came home in second place, behind the jubilant Di Grassi, who now tops the standings, with one race to go for the first time this season.
Bird stars with drive to sixth
A disastorous qualifying saw New York double race winner Sam Bird start 18th for DS Virgin Racing, but some swift work at the stops saw him come home in sixth place, ahead of Prost, who is yet to claim a podium this season.
The other points scorers were Evans for Jaguar in eighth, Frijins for Andretti and Rosenqvist hanging on to snatch the final point in 10th.
|1st||Lucas di Grassi||Abt Schaeffler Audi Sport||35 Laps||25|
|4th||Sebastien Buemi||Renault E.Dams||+8.256s||12|
|5th||Daniel Abt||Abt Schaeffler Audi Sport||+8.592s||10|
|6th||Sam Bird||DS Virgin Racing||+8.913s||8|
|7th||Nicolas Prost||Renault E.Dams||+10.058s||6|
|8th||Mitch Evans||Jaguar Racing||+10.457s||4|
|10th||Felix Rosenqvist||Mahindra Racing||+16.764s||1|
|12th||Jerome D'Ambrosio||Faraday Future Dragon Racing||+20.229s||0|
|14th||Nelson Piquet Jr||NEXTEV NIO||+23.145s||0|
|15th||Antonio Felix da Costa||Andretti||+34.786s||0|
|16th||Oliver Turvey||NEXTEV NIO||+46.996s||0|
|DNF||Loic Duval||Faraday Future Dragon Racing||Not Classifed||0|
|DNF||Jose Maria Lopez||DS Virgin Racing||Not Classified||0|
|DNF||Nick Heidfeld||Mahindra Racing||Not Classified||0|