Tens of thousands of Rangers fans are in Seville ahead of one the biggest matches in the club's history.
Police expected up to 100,000 supporters of the Glasgow team to travel to the Spanish city for the Europa League final.
They will be joined by 50,000 fans of German side Eintracht Frankfurt.
The vast majority of those who have travelled do not have tickets for the game in the 42,700-capacity Estadio Ramon Sanchez Pizjuan.
Only 9,500 tickets were originally sold to Rangers fans, although more are believed to have been made available in recent days.
Ticketless Rangers fans will be able to watch the match at the 57,000-capacity Estadio La Cartuja in the north of the city - where Celtic lost the 2003 Uefa Cup final to Porto.
Former Rangers captain John Greig, who led the team to victory in the European Cup Winners' Cup Final in Barcelona in 1972, wrote an open letter to fans ahead of the final urging them to be "ambassadors" and show the "absolute best" of the club.
He added: "To see Rangers in a European final is something many of us thought would not be possible again, and I've been so taken by the incredible lengths you are going to in order to reach Seville to back the team out there.
"It is vital that we all act responsibly and remember the values that this institution stands for."
Seville Police said they were prepared for large numbers of supporters in the city for the match - which kicks off at 20:00 - with about 5,000 officers on duty.
Many bars in Seville will be closed on Wednesday, but fans will be able to watch the game on big screens around the city.
Rangers have travelled from across the globe to watch the match, with some travelling from as far as Australia despite not having tickets for the game.
Brian, originally from Nairn, spent 40 hours travelling to Seville from Sydney. He bought a match ticket on Tuesday for 1,600 euros (about £1,350) and reckons he has spent about £5,000 on the trip so far.
"And that doesn't include any drinks, so you can double that!" he told BBC Scotland. "It is money well spent. I didn't travel from Australia not to see the game.
"I am 54, I have been a Rangers fan my whole life and will probably never see this again in my lifetime."
More than 400 flights arrived in the city on Tuesday, with a similar number - including 16 charter flights from Glasgow Airport - expected on Wednesday, with trains and coaches travelling to the city also full.
By Tom English, BBC Scotland in Seville
They've come in from every conceivable direction. The multiple charters out of Glasgow are the least of it.
Some have scrambled to Seville via Marrakesh in Morocco, others have gone Glasgow-Gatwick-Bilbao-Seville, Glasgow-Luton-Lisbon-Seville, Edinburgh-Bergamo-Milan-Madrid-Seville.
There are tales of expats coming up from the Southern Hemisphere. The Rainbow Hot Air Balloon company took calls from folk wondering if they could book something to get them to Spain. The owners thought it was a wind-up at first. It wasn't.
There are hundreds if not thousands of stories knocking about and they will become legend if Rangers beat Eintracht Frankfurt on Wednesday night.
They'll be passed down the generations, some real, some exaggerated or invented, but magnificent nonetheless. "My granda cycled to Seville with his big mate Archie on the handlebars."
There's a fantastic madness to it all, a uniqueness. This is Rangers' second European final in half a century. Who knows when they are going to be in another one and how many of their fans who have made this trip will be alive to see it.
Rangers were last in a European final in 2008, when they lost 2-0 to Russian side Zenit St Petersburg in the Uefa Cup final in Manchester.
They have now reached five finals, which is as many as every other Scottish side combined.
The Scottish club has already knocked out German giants Borussia Dortmund and RB Leipzig on their route to the final, and will be looking to add Eintracht Frankfurt to that list as they attempt to win a major European trophy for the second time in their history.
This will be Eintracht's third European final. They lost in the 1960 European Cup against Real Madrid at Hampden before beating Borussia Monchengladbach to lift the 1980 Uefa Cup.
The German side are unbeaten in this season's tournament, and have defeated Barcelona and West Ham United in previous rounds.
BBC Scotland's John Beattie told the Drivetime programme that fans from both clubs were mingling and it was "pretty relaxed" as supporters started to gather in Seville on Tuesday.
"It is stiflingly hot - 32, 33C - and the squares are packed with the red, white and blue colours of Rangers and the black of Eintracht Frankfurt supporters," he said.
"These meandering back streets are thronged with Scots and Germans but the truth is most of these fans don't have tickets."
He added: "There are fun zones, outdoor beer gardens and food stalls, penalty shoot-out areas, a place where you can get your photo taken with the cup. It is all very good-natured, a party atmosphere."
Clifford Stott, a professor in crowd psychology at Keele University, told BBC Radio Scotland there would be an added challenge for the police in Seville because the largest crowds would be at neighbouring stadiums where the match is being shown on big screens.
Prof Stott said that Spanish policing could be "quite provocative and very heavy handed" but officers would need to address "the legitimate ambitions of the vast bulk of supporters coming across" rather than just looking out for any troublemakers.
Five Eintracht Frankfurt fans were arrested for disorder on Tuesday evening, with one Rangers fan treated for a head injury - but police said there were no serious injuries
Meanwhile, large numbers of Rangers fan who have not travelled to Spain are expected to gather in the centre of Glasgow on Wednesday evening.
Police Scotland said they would do everything they could to reduce disruption, with the city council saying it had removed memorial benches in George Square, some of which were damaged last year during celebrations of Rangers' Scottish Premiership title triumph last year.