But the Swans should have been level when a fine cross from Ronald came through to Widell at the far post. The Swede had stolen a march on his marker but hit his shot into the ground and it flew wide.
Instead the French side doubled their lead when Pagis stole in between two defenders and guided a low finish across goal and into the far corner of the net.
And the visitors extended their lead further before the break as Bamba converted from the spot after Arthur Parker had brought down Igor Silva.
The first big chance of the second half fell to the Swans as a lovely flowing move sent Galbraith through the middle. The Northern Ireland international teed up Ronald as the cover came across, but the Brazilian’s final effort was saved.
Widell then volleyed over after Lorient had failed to clear Galbraith’s delivery from a free-kick, but the Swans soon pulled a goal back when Cullen scored from the spot after Ronald had been fouled as he broke into the Lorient area.
Eom and Inoussa were introduced and immediately were heavily involved in two incisive Swansea moves, with both just not able find a teammate with their final ball.
Cullen had a fine header from an Inoussa cross ruled out for offside as Swansea finished the stronger of the two sides, while Josh Tymon sent a free-kick narrowly over the bar from an acute angle.
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Swansea City:Â Lawrence Vigouroux, Josh Key, Arthur Parker, Cameron Burgess (captain), Josh Tymon; Jay Fulton, Goncalo Franco, Ethan Galbraith (Ollie Cooper 80), Melker Widell (Zeidane Inoussa 65), Ronald (Jisung Eom 65); Liam Cullen (Bobby Wales 80).
Unused Substitutes: Andy Fisher, Joel Cotterill, Sam Parker, Cameron Congreve, Sebastian Dabrowski, Iestyn Jones.
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FC Lorient: Benjamin Leroy, Igor Silva, Montassar Talbi, Laurent Abergel, Mohamed Bamba, Aiyegun Tosin, Gedeon Kalulu, Darlin Yongwa, Arthur Avom, Joel Mvuka.
Substitutes: Noah Cadiou, Bandiougou Fadiga, Jeremy Hatchi, Lucas Leaudais, Jean Victor Makengo, Fornose Mendy, Isak Monnier, Stevan Siba, Sambou Soumano, Bingourou Kamara, Bahliseni Fofana.
Referee: Iwan Griffith
Attendance:Â 6,063