The moment Let’s Eat Grandma won me over was when half of the English duo played a saxophone solo. It came after about 15 minutes of playful synth-pop that veered between start-stop pummeling and more dramatic constructions full of interlinked segments and lyrics grounded in social media-age ennui. Then, in the final minute of set highlight “Falling Into Me,” Jenny Hollingworth picked up a sax that had just been sitting there and played it to close out the song. It was a creative touch and reflective of the duo’s ability to time everything just right early in the afternoon Friday at the Red Marquee.

Hollingworth and Rosa Walton started their first Fuji Rock set off with their most right-for-the-forehead pop cuts. Opener “Hot Pink” built from subdued verses up until a hook constructed from jagged beats and the pair’s in-synch singing, creating a dizzying chorus that had folks bopping along. Jittery rush-of-attraction cut “It’s Not Just Me” and the aforementioned “Falling Into Me” kept the energy up. It was solid radio-eyeing pop from a pair of artists with a knack for writing knotty numbers highlighted by of-the-moments observations (few artists know how to write about smartphones like these two).

And then out came the sax, and what could have been a solid but still-in-development went in a much more interesting direction. The two took part in a kind of secret handshake a few times during their set — somewhere between patty cake and touchdown celebration — and during slower songs indulged their inner theater kid by sprawling out on the floor. What felt like a lull late in their set — a little too gloomy, a little too slow — soon revealed itself as a masterstroke of pacing on slow-burning finale “Donnie Darko,” a ten-minute-plus cut that eventually burst into a synth-pop flameout that saw Walton spinning around the stage while Hollingworth ran around the front giving punters high fives. What could have been a conventional end-credit closing number veered into something far more offbeat, fitting for the duo.