St Johnstone have appealed to supporters to be on their best behaviour when they kick-off their Europa League campaign on Thursday night.
Tommy Wright's side will begin their quest for a group-stage place when they host Lithuanian outfit FK Trakai at McDiarmid Park on Thursday.
But Saints chiefs are worried they could fall foul of UEFA disciplinary chiefs if fans step out of line.
The Perth outfit were fined £16,000 in 2014 after a supporter waved a Palestinian flag during a qualifying clash with Slovakian side Spartak Trnava, breaching strict rules put in place by European football's governing body on political gestures.
Now the club have urged the Saints faithful to keep their displays in check and to leave flares and smoke bombs at home.
A statement read: "As we prepare for a return to the European stage on Thursday, we would just like to take a few moments to highlight the importance of supporter behaviour at the games.
"Saints fans have a great reputation for following their team. We have had no trouble at home or away games in Europe and the club has little doubt that our fans will enjoy Thursday's home leg against FK Trakai in a responsible manner as will those who travel to Vilnius next week.
"Nevertheless, our supporters will be aware that the club has fallen foul of UEFA on previous occasions - in 2014 we were fined 18,000 Euros when one supporter briefly waved a Palestinian flag and we were previously censured when a young supporter ran onto the pitch in celebration of a goal.
"Both legs of the tie will be in the presence of UEFA delegates who will report any issues back to the governing body and any breaches will likely hit the club hard financially.
"So, please - keep it noisy, keep it colourful but keep it within the bounds of what is allowed and absolutely no pyros please."
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