The youngest driver in the field at 22 looked to have failed to hold off a late charge from DS Techeetah’s Antonio Felix Da Costa who started in 10th after a robust overtake with a few minutes to go.
But the German - who ended a 609-day duck for German victors in Formula E - made the most of Da Costa’s overheating issues in the final seconds of the race with just two corners to go to bring the sell-out crowd to their feed and take the chequered flag for the first time.
Panasonic Jaguar Racing’s Mitch Evans finished in third after starting on pole while reigning champion Jean-Eric Vergne and previous Championship leader Alexander Sims were two of seven retirees – a record – in a fiery race matching the track temperature.
Qualifying set the tone for the day with crashes, 360 spins and some sublime driving headlined by Evans who took pole after a fabulous performance – fastest in both qualifying and Super Pole, 0.275 quicker than Guenther in second.
Felipe Massa started fourth on the grid after remarkably setting the exact same time as Mahindra Racing’s Pascal Wehrlein in Super Pole – the German starting third due to setting the time first.
From the lights going green the early battle was between Championship leader Sims and TAG Heuer Porsche’s Andre Lotterer as Sims bulldozed his way up five spaces from 15th in the first few minutes. Lotterer, never won to shirk hard racing, decided to fight back with both suffering contact and both ending up retired in the pits.
ROKiT Venturi Racing had their own moment of hot-headedness midway through the race as Massa was forced wide into the wall by his own teammate Edoardo Mortara which saw him lose two places from fourth – the Brazilian ending up ninth.
Moments later Guenther used his final moments of ATTACK MODE to take the race lead from Evans in a great fight – but the extra 25kw showed exactly how much it gives as the German flew past on the long straight.
The suspicion was the high heat – with track temperatures up to 40 – was having an impact on the cars as numerous teams that had looked quick in the first half of the race began to fade.
The two DS Techeetah cars, however, began closing the gap as champion Vergne climbed eight places into third position with teammate Da Costa slipstreaming into fourth.
However, Vergne had been in a podium position for mere minutes before his front wing began rubbing on his tyre. The Frenchman refused to pit with the friction causing smoke to fly all over the track behind him before the debris eventually came off. He soon was forced to pit but was applauded off by the fans after the thrilling piece of driving.
Then it was all on teammate Da Costa who went past Wehrlein and Evans into second – now the only man who could catch Guenther and with a couple of minutes left some argy-bargy on turn 10 took the Portuguese into first.
Towards the back of the grid Lucas Di Grassi had also produced a stunning drive through the grid to climb from 22nd to seventh but all eyes were on the two in front for the final two laps as Guenther discovered his battery temperature was in much better shape.
And he made the most of Da Costa having to slow to slip past him in the final seconds and take his first ever Formula E victory. This also took the German to fourth in the Driver’s Championship while new Championship leader is Mercedes-Benz’s Stoffel Vandoorne after taking eight points from sixth place.
The ABB FIA Formula E Championship will return with the Mexico City E-Prix on February 15.