Gunther, who lost a maiden podium last time out in Saudi Arabia for overtaking under the safety car, claimed his first FE win, with polesitter and longtime leader Mitch Evans rounding out the podium for Jaguar.
At the start, Evans held the lead off the line, while Mahindra Racing’s Pascal Wehrlein forced his way by Gunther – who had started second – on the tight off-track approach to Turn 2, which the field cut on mass throughout the race.
Most of the action in the early stages happened in the pack well behind the leaders, as Evans marshalled his lead up front. The Jaguar driver went for an aggressive early attack mode strategy, taking his first activation on lap eight of what would become a 40-lap race.
He used his second activation five laps later and although he held the lead of the majority of the race, he was vulnerable to attack from behind as his rivals cycled through to take their time in the higher power mode.
Gunther used his second time with the 235kW mode to move back ahead of Wehrlein, and he then attacked Evans at the start of lap 19, although that move was rebuffed. But later on that tour, Gunther swept around the outside of the blind, rapid left of Turn 9 to take the lead.
Behind the leading pair, da Costa and his team-mate Jean-Eric Vergne were making their way up from 10th and 11th on the grid, muscling their way by their feuding rivals – including Venturi pair Edoardo Mortara and Felipe Massa, who clashed at the Turn 10 hairpin on lap 15.
Vergne closed in and got ahead of Wehrlein to run third approaching the race’s final quarter, but damage he had picked up in the rough early exchanges came back to haunt him as his damaged left-front wheel cover began to rub heavily on his tyre – eventually breaking loose and deflating the tyre. That dropped Vergne to fifth behind da Costa and Wehrlein, but he was later forced to come into the pits and retire due to the damage he had sustained.
Up front, Gunther had pulled a significant two-second gap over Evans, who rapidly came under pressure from da Costa, with the former BMW driver getting by with another sweep around the outside into Turn 9 on lap 34.
Da Costa immediately set about demolishing Guenther’s lead and they ran nose to tail from the start of lap 37. Towards the end of that tour, da Costa dived to the inside of Turn 10 and biffed his rival wide to take the lead.
It briefly looked as if that would settle the result, but da Costa was suddenly informed he needed to slow down due to his battery temperatures in the dying laps, which gave Gunther the chance to retake P1. Da Costa rebuffed a forceful move from Gunether at Turn 1 on lap 39, but on the final tour Gunther was able to race around the outside on the run to Turn 9 and swept in the lead at the death, shooting clear to win by 2.067s.
Evans was beaten to the line by Nyck de Vries, but the Mercedes driver was immediately dropped back to fifth due to a five-second penalty he had been handed for a so far unspecified technical infraction.
De Vries had dropped down the order from eighth on the grid but fought his way back into contention, although his penalty left him behind Wehrlein in the provisional result.
Stoffel Vandoorne was classified fifth after a similarly up-and-down race to his team-mate de Vries, with Audi’s Lucas di Grassi taking seventh having started 22nd after his qualifying issues. James Calado took eighth ahead of Massa, with early spinner Sam Bird boosted up to 10th by immediate post-race penalties for Daniel Abt (eventually 14th) and Buemi (13th).
Unlikely superpole star Oliver Turvey ran with the leaders early-on, but the British driver was eventually shuffled back to 12th at the flag.
Seven drivers were not classified – including Vergne – with Jerome D’Ambrosio and Brendon Hartley stopping in the pits late-on. Mortara did likewise, but his retirement was as a result of damage picked up in a clash with da Costa.
Andre Lotterer was running at the flag but was 12 laps down for most of the race after an early clash with Alexander Sims that eventually caused the BMW driver and former championship leader to stop on-track with damage. Neel Jani also retired in the pits early on following the early melee at the lower end of the order that also involved Lotterer and Sims.