Nick Cassidy blew a chance to massively extend his Formula E World Championship advantage by spinning out of the Portland lead on the penultimate lap.
Though his Jaguar team-mate Mitch Evans crossed the line first, a five-second penalty for contact with McLaren’s Jake Hughes dropped Evans to eighth and meant Antonio Felix da Costa picked up a third win in four races.
But Porsche had cause for disappointment too because da Costa’s title-chasing team-mate Pascal Wehrlein gained just one point on Cassidy as he only managed to finish 10th.
Cassidy appeared to be driving another energy-saving masterclass - hanging back in 13th early on then surging from there to first within a couple of laps before half-distance.
He won a lead fight with da Costa and was keeping Evans at bay on the road when he ran wide into the Turn 10/11 chicane at the end of the lap on the penultimate tour, slewing onto the grass and spinning down to an eventual 19th.
With Evans’s penalty - which he felt was hugely unjust - kicking in as he crossed the line, da Costa found himself going from third behind a Jaguar 1-2 to first within minutes. Evans had started from pole and was a frontrunner throughout. Hughes picked up a puncture in their incident and finished a lapped 21st.
Robin Frijns ended up top Jaguar driver for its customer team Envision in second ahead of DS Penke’s Jean-Eric Vergne.
Edoardo Mortara’s fourth for Mahindra was a season-best result. Reigning champion Jake Dennis was sixth for Andretti behind Abt Cupra driver Nico Mueller.
Wehrlein’s tactic of leaving his attack mode trips late appeared to backfire as he couldn’t make any progress back from 10th once the pace picked up in the closing laps. He is also under investigation for a clash that ended Maserati driver Maximilian Guenther’s race and is still 24 points behind Cassidy despite the Jaguar racer’s blunder.
Dennis’s Andretti team-mate Norman Nato had actually been fastest in qualifying but a full-course yellow infringement in final practice earned him a third reprimand and triggered a 10-place grid penalty. He converted 11th on the grid to first in the race within two laps then seemed to sacrifice himself with a long stint in the energy-inefficient lead and finished 13th.