"It's too many people with too much alcohol, the majority without tickets for the game and lots of construction sites around the city, a recipe that could lead to serious problems," Juan Carlos Castro Estevez, Spain's General Commissioner for Citizen Security, said at a briefing with high-ranking National Police officers on Tuesday.
He said 100,000 Rangers fans were expected with 50,000 from Frankfurt as the two clubs battle for the title that will qualify them for next season's Champions League.
While warning that the policing operation will be one of the most "difficult challenges they have ever had," he said he was confident the showpiece could pass off without major problems.
"We are trying to do everything right and we have a lot of experience with situations like this, although that does not mean that there will be no problems," he said.
"We will host two fanbases that drink a lot. These citizens, who are used to drinking warm beer in their countries, when they find our fresh and cold beers, will drink even more.
"But we sincerely believe that we have sufficient and prepared units to counteract the problems."
While all roads lead to Seville for the fans, Castro said he was not quite sure how they would all arrive.
"All the trains from Madrid and Malaga are sold out and we are expecting a massive arrival of charter flights to Seville, Mallorca, Canary Islands, Malaga, Jerez and Faro where we believe around 30,000 Rangers fans will stay, coming to Seville by buses on Wednesday," he said.
"But we can't know for sure how many will arrive by car, buses and boats. Eintracht only had 5,000 tickets to their quarterfinal at Barcelona and 30,000 showed up somehow at Camp Nou."
The two clubs have only been allocated 10,000 tickets each for the final at the 42,000 capacity Pizjuan Stadium.
Rangers are playing in their first European final since the 2008 Europa League when they lost to Zenit St Petersburg in Manchester -- an occasion marred by crowd violence.
The Scottish club have not won any European silverware for 50 years while Eintracht Frankfurt are bidding to end their 42-year wait for European glory, having won the UEFA Cup in 1980.
Spanish authorities have deployed 3,100 National Police officers to Seville where three fanzones are being prepared. Almost 2,000 Guardia Civil and local police will be deployed in the city.
Castro said construction sites around the city were being "protected" so that fans cannot use rubble as weapons.
"There is no rivalry [between Rangers and Frankfurt], but it is concerning that the political ideology from the two fanbases are different, Eintracht being from the left and Rangers more to the right. The extremists from both sides could cause serious trouble."
To minimise the risk of confrontations the two sets of fans will be kept in separate areas, 5.5km apart, before kickoff.