European Challenge Cup
Bayonne (14) 17
Tries: Bruni, Lopez Cons: Lopez 2, Pen: Segonds
Scarlets (13) 16
Tries: Evans Con: Lloyd Pens: Lloyd 3
A late Bayonne penalty denied Scarlets a first victory in France for a decade.
Ioan Lloyd nudged the visitors ahead for the first time on 74 minutes at a wet and windswept Stade Jean Dauger.
But Italian referee Gianluca Gnecchi reversed a penalty moments later after Archer Holtz' reaction to foul play and replacement fly-half Joris Segonds struck the winning kick.
It was a tough call on Australian prop Holtz who had otherwise impressed on his club debut, including a try-saving tackle.
But it was even harsher on Scarlets who looked on course for a first win on French soil since beating Racing 92 in 2014.
Until then they had given a masterclass in defence, discipline and determination to keep it a one-point game.
Rodrigo Bruni and Camille Lopez both crossed for Bayonne - fifth in the Top 14 - but Scarlets clawed their way back through the boot of Lloyd before hooker Shaun Evans burrowed over on the stroke of half-time.
More to follow
Bayonne: Cheikh Tiberghien; Nadir Megdoud, Guillaume Martocq, Manu Tuilagi, Mateo Carreras; Camille Lopez (capt), Guillaume Rouet; Martin Villar, Lucas Martin, Pieter Scholtz, Denis Marchois, Veikoso Poloniati, Rodrigo Bruni, Baptiste Heguy, Uzair Cassiem.
Replacements: Torsten van Jaarsveld, Andy Bordelai, Pascal Cotet, Baptiste Chouzenoux, Giovanni Habel-Kuffner, Baptiste Germain, Joris Segonds, Tom Spring.
Scarlets: Ioan Nicholas; Tom Rogers, Joe Roberts, Eddie James, Ellis Mee; Ioan Lloyd, Efan Jones; Kemsley Mathias, Shaun Evans, Sam Wainwright, Alex Craig (capt), Jac Price, Jarrod Taylor, Dan Davis, Vaea Fifita.
Replacements: Isaac Young, Sam O'Connor, Archer Holz, Sam Lousi, Max Douglas, Archie Hughes, Charlie Titcombe, Macs Page.
Referee: Gianluca Gnecchi (FIR).
Assistant referees: Franco Rosella &Alex Frasson (Ita) (WRU).
TMO: Stefano Roscini (FIR).