Though Lyon cruised through the league phase in top spot, Celta came into the encounter in far superior form, and that showed in their directness in the early stages.
Borja Iglesias registered the Sky Blues’ first shot on target, and while Corentin Tolisso did similarly at the other end, it was the hosts who forged ahead.
Countering after a spell of Lyon possession, Williot Swedberg powered down the left and bobbled a cross to Javir Rueda, who swept in from the centre of the area.
The visitors struggled to respond, but they did have most of the subsequent possession and troubled through Endrick on more than one occasion.
A similar trend continued after half-time too, though Lyon’s dominance of the ball increased even further.
Celta, though, were in trouble when Iglesias raised his arm when challenging Clinton Mata, and referee Erik Lambrechts decided that was enough to show a second yellow and reduce the home side to 10 men for the final 35 minutes.
Ionuț Radu stopped Endrick and Tyler Morton's efforts, keeping his side ahead for the time being, before Steeve Kango hit the outside of the post, nearly scoring on his professional debut for Lyon.
Radu produced his best save yet with 15 minutes remaining to keep out Roman Yaremchuk’s close-range header.
But the Romanian stopper’s fortune finally ran out with just a few minutes to play when he couldn’t deal with the power of Endrick’s low shot from distance, and could only fumble it over the line.
Celta’s failure to hang on may well come back to bite them when they travel to France for the second leg next week, as might Iglesias’ suspension for that game.
While Lyon’s remarkable 13-match winning run between December and February now seems like a distant memory, their courage to draw level in this one will inspire confidence that they can progress to the UEL quarter-finals for the second successive season.
Flashscore Man of the Match: Ionut Radu (Celta Vigo)