Martin Jol admitted Fulham suffered an "awful night" in Poland after defeat to Wisla Krakow was compounded by Moussa Dembélé's harsh-looking red card and an injury to Orlando Sa.
The Belgium international's dismissal paved the way for the Polish champions to secure their first Group K points, with David Biton striking the all-important goal in a 1-0 win.
The incident occurred during an innocuous passage, when Dembélé pushed over Gervasio Nunez after he caught him on the back of the ankle.
The Argentinian midfielder went down clutching his face despite being pushed at shoulder height, leading referee Martin Hansson to hand Dembélé a straight red card.
"You could say it was a frustrating evening," Jol said. "Before the sending off I think we were in control. Then we got a straight red card and that makes it difficult for any team. It was an awful night for us."
Hansson famously missed Thierry Henry's handball during France's World Cup play-off victory against the Republic of Ireland.
Jol's sense of injustice in Poland was strengthened by the Swedish referee's failure to send off Ivica Iliev in the opening minutes and decision not to give Osman Chavez a second yellow card.
"I would say that in the first minute one of my players was kicked and it should have been a red card," Jol added. "But it was disappointing in the second half. Pajtim Kasami had his shirt pulled and it should have been [Chavez's] second yellow card."
Orlando Sa hobbled off with what looked to be a hamstring injury in the second half. "It could be a real problem," Jol said of the injury. "It could be weeks [he is out for]."
Wisla Krakow (4-4-2): Pareiko; Jaliens, Chavez, Lamey, Diaz; Gargula (Brud, 79), Nunez, Kirm (Czekaj, 90), Wilk; Biton, Iliev (Boguski, 86). Substitutes not used Jovanic (gk), Paljic, Jirsak, Genkov.
Fulham (4-4-2): Schwarzer; Kelly, Hangeland, Hughes, Briggs (Frei, 87); Duff, Gecov (Sidwell, 75), Etuhu, Sa (Kasami, 58); Dembélé, Johnson. Substitutes not used Etheridge (gk), Riise, Baird, Trotta.
Referee M Hansson (Sweden).