Newport Gwent Dragons lost their third successive Amlin Challenge Cup match despite a effort in Perpignan.
A dominant first-half display allowed Perpignan to open a 15-3 half-time lead as full-back Porical Jerome slotted over five penalties.
The Dragons hit back straight after the interval with an opportunist Aled Brew try, converted by Matthew Jones.
But Charles Geli's try restored the home side's cushion and Robins Tchale-Watchou crossed in the last minute.
Despite the win, the French side have lost top spot in Pool Four after Exeter earlier secured a bonus-point victory against whipping boys Cavalieri Prato.
The two clubs will meet in Exeter on 21 January to decide who proceeds into the quarter-finals.
The Dragons, missing six key players through injury, put themselves in a strong position to cause an upset when Brew pounced on a loose ball to race to the tryline.
Jones' conversion cut the gap to five points with most 35 minutes remaining, but a short lineout throw caught the Dragons napping, allowing hooker Geli to charge unopposed down the left flank to score in the corner.
Porical slotted over the conversion superbly from the touchline.
Geli'r try on 56 minutes followed immediately after Dragons lock Rob Sidoli was sent to the sin bin, but the numerical advantage swung in the visitors' favour two minutes later when two Perpignan players followed him.
Armnad Battle was first penalised for a spear tackle on Jones and then Tchale-Watchou's high tackle on Martyn Thomas resulted in another yellow card.
But the Dragons failed to score in the following 10 minutes, and Tchale-Watchou wrapped up the victory for Perpignan with a last-minute try.
Perpignan: Porical, Sid, Marty, Mermoz, Plante, Hume, Mele, Pulu, Geli, Bourrust, Britz, Taofifenua, Le Corvec, Perez, Tonita.
Replacements: Laharrague for Porical (59), Batlle for Sid (52), Cazenave for Mele (70), Schuster for Pulu (52), Tincu for Geli (75), Mas for Bourrust (52), Tchale-Watchou for Taofifenua (54), Chouly for Le Corvec (30).
Sin Bin: Tchale-Watchou (58), Batlle (58).
Newport Gwent Dragons: M. Thomas, Harries, Hughes, Tuilagi, Brew, M. Jones, W. Evans, N. Williams, S. Jones, Buck, A. Jones, Sidoli, Lydiate, L. Evans, Faletau.
Replacements: Riley for Tuilagi (75), S. Jones for M. Jones (70), J. Evans for W. Evans (75), Price for N. Williams (71), Way for Buck (61), Brown for A. Jones (75). Not Used: Buckley, Gustafson.
Sin Bin: Sidoli (55).
Ref: Peter Allen (RFU).