Rangers will bring the largest-ever number of fans to Bilbao this week with Spanish police expecting 5,000 supporters to travel to Spain.
And they are on high alert because of an expected huge influx of Greek fans too for a basketball match the day before Rangers play in the city and scenes of mayhem in the last round when Roma visited.
Rangers managed to secure a goalless draw in the Europa League quarter final first leg despite having to play the vast majority of the game with ten men after Robin Propper was sent off.
They have been handed an official allocation of 2,600 for the second leg at the San Mames ground, but Spanish police forces are reportedly been informed by their Scottish counterparts that 5,000 Rangers fans are expected to travel even though plenty won't have tickets.
There is already a massive nightclub selling tickets for Rangers fans at nearby Ernadio which will open from 2.30pm on the day of the game until 4.30am after it, with tickets being sold for 25 Euros.
No other club have taken as many supporters to Bilbao and tensions have been heightened because of the FIBA Europa Cup basketball final first leg between Bilbao Basket and PAOK Thessaloniki on Wednesday.
The capacity of the Bilbao Arena where the game will be held is 10,000 and PAOK are expected to bring a couple of thousand fans to the city for the basketball game.
Bilbao police have already announced they will install a security cordon outside the stadium after trouble when Roma visited in the last round.
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Bars were wrecked, bins were set on fire, police attacked, ambulance medics were threatened, cars were damaged and street furniture was flung around the city, leading to dozens of arrests.
Bilbao's mayor, Juan Mari Aburto, promised afterwards: "We are working with the Basque police force, the city police and the Government to increase security after an entirely unacceptable night.
"For the Rangers game, we will closely coordinate with the Scottish police to gather intelligence and will decide upon appropriate restrictions.
"But you can be sure there will be tighter controls around the surrounding area of the stadium.
"I want to make it clear to those people who caused this damage - we don't want you with us. I call on society to stand up to them.
"We cannot accept attacks against the police forces as normal, we cannot normalise attacks on medical staff in the ambulances.
"In future, the police will do what they have to do."
Rangers supporters have been invited to buy tickets for the giant nightclub and are promised 'a day to remember in a location just 15 minutes from San Mames Stadium, the airport, or the city center.
"The party doesn't end after the match."
