Nicolas Prost fended off Scott Speed to clinch his maiden Formula E win on the streets of Miami.
The son of four-time F1 world champion Alain Prost, passed Daniel Abt for the lead with just two laps of the race remaining, but was then forced to defend from a charging Speed in the closing stages.
In the end, Prost just managed to hang to take the chequered flag by 0.433 from Speed, who was making his Formula E debut for Andretti Autosport.
Abt, who led the race after the mandatory pit stops, secured his best result of the season in third just ahead of Dragon Racing's Jerome D'Ambrosio.
Pole-sitter Jean-Eric Vergne suffered overheating problems which saw the early leader drop to 18th having lost two laps to the leaders.
Prost's victory has lifted the Frenchman to the top of the championship standings having now opened up a seven point lead over Lucas di Grassi.
“I need to take every race one by one and you need to be very careful in this championship,” Prost said.
“We race around street circuits so mistakes are just around the corner and can happen very easily.
“Next race I will take the same approach and try to pick up as many points as possible. After the second race in London we'll see where we are.
“I'm really happy to be leading this championship because there are some super drivers involved – I think it's one of the top series in terms of driver line-up.”
The Formula E Championship heads to Long Beach for round six on April 4.
Creventic 24H Series – Mugello 12 Hour
HB Racing Team Herberth emerged victorious in the Creventic International Series Mugello 12 Hour.
The Porsche 997 GT3 R driven by Daniel Allemann, Ralf Bohn, Robert Renauer and Alfred Renauer took the victory by almost a lap from the Ram Racing Mercedes SLS AMG GT3 of Tom Onslow-Cole, Adam Christodoulou and Paul White.
The final place on the podium went to the Hofor Racing Mercedes SLS AMG GT3 of Chantal Kroll, Michael Kroll, Roland Eggiman, Kenneth Heyer and Christiaan Frankenhout.
MARC Cars Australia claimed the SP2 class with the #91 Focus V8 entry of Keith Kassulke, Peter Leemhuis, Jake Camilleri and Ryan McLeod finishing the race 14th overall.
The sister entry piloted by Australian F3 runner-up Ben Gersekowski, former BTCC driver James Kaye and Britcar stars Javier Morcillo and Manuel Cintrano finished third in class.