Real Madrid against Bayern Munich is the most played match in UEFA competition history and, possibly, the most heated cross-border rivalry in all of European football.
Two clubs representing the north and south of the continent, and with a lot in common, have faced off 24 times over the last four decades. But the "European Clasico" has had almost as much controversy and bad feeling as its La Liga namesake.
Refereeing decisions in particular have sparked debate over the years, with Bayern currently feeling the aggrieved party following a number of decisions as Madrid won through 6-4 on aggregate in last season's quarterfinals.
But whether Cristiano Ronaldo was offside or not when scoring in the second leg is pretty minor by the standards of this fixture, as shown by a look back at five of their most infamous past meetings.
1. "El loco del Bernabeu"
Bayern's first ever visit to the Bernabeu came in the 1975-76 European Cup semifinals, with the Bundesliga team heading for their third successive trophy.
Madrid went 1-0 up early after ex-Bayern midfielder Gunter Netzer sent Roberto Martinez through on goal, but the visitors took advantage of Madrid's players claiming a corner to sweep upfield and equalise through Gerd Muller. The anger inside the ground grew early in the second half when Martinez left the field with a facial injury suffered in an accidental clash with Germany international goalkeeper Sepp Maier.
As Madrid pressed for a winner, referee Erich Linemayr waved away late loud penalty appeals. On the final whistle a fan leaped from stands, and raced across the pitch to punch the Austrian official in the face, despite Uli Hoeness' attempts to intervene. Although a photographer captured the moment, stewards and police somehow managed to let the invader escape back into the crowd.
El 31 de marzo del 76, en un partido de semifinales de la Copa de Europa entre el Bayern y el Real Madrid, en un ambiente muy caldeado un aficionado saltó al césped y alcanzó al árbitro austriaco Linemayr con un directo al rostro, pasó a la historia como 'El Loco del Bernabéu'. pic.twitter.com/wUc41Dffo1
- AS Historia (@AS_Historia) April 19, 2018
UEFA punished the Bernabeu's lax security with a stadium closure for two seasons, later dropped to one year on appeal. Two decades later AS finally tracked down "El Loco del Bernabeu," [The crazy of the Bernabeu] who explained that he had been attending the game with his heavily pregnant wife high in the stands, and grown so incensed by Linemayr's decisions that he had excused himself to use the stadium toilets, but instead worked his way down to pitch level. While insisting on remaining anonymous, he claimed to now be sincerely sorry for his actions.
Bayern won the return leg 2-0, thanks to two Muller goals, and then beat Saint-Etienne in the final.
2. Bayern 9-1 Real Madrid
It seemed like a good idea at the time for Madrid to go to Munich for a preseason friendly in early August 1980, even though the La Liga season started much later than the Bundesliga that year.
Just 45 minutes into the game, the decision to take the cash on offer looked less smart, as a match-fit Bayern were 7-0 ahead of a Madrid side still mentally and physically on the beach, with Hoeness having grabbed a hat trick and Karl Heinz Rummenigge a double. The Germans eased off in the second half for a 9-1 final score.
Although only an exhibition game, it is still remembered as one of Madrid's biggest ever humiliations, and for then-Blancos coach Vujadin Boskov's attempt to relieve the tension afterwards.
"I'd prefer to lose one game by nine goals, than nine games by one goal," was a joke which is marginally funnier when delivered in Serbian-accented Spanish.
3. Juanito stamps on Matthaus' head
The most serious incident between the teams, and among the worst on-pitch violence in all of UEFA competition history, came in a 1987 European Cup semifinal first leg at Bayern's Olympiastadion.
Madrid began badly, and found themselves 3-0 down inside 37 minutes -- with the second goal a penalty converted by Matthaus after a debatable decision by Scottish referee Bob Valentine.
Madrid were being humiliated, and a reaction came after Matthaus fouled Chendo. When the right-back jumped to his feet, eager for a confrontation, Matthaus exaggerated the contact and fell to the ground. Enter Juanito, who brushed past Valentine to first stamp on Matthaus' torso, then push the referee away so he could slam the same boot down hard on his prone opponent's jaw.
Although the German recovered sufficiently to later convert a penalty as Bayern won 4-1 on the night, Juanito's stamp earned him a record five-year ban from UEFA. Madrid regained some pride by winning the return 1-0, although objects thrown from the stands saw the Bernabeu ordered closed (again) for their first two games the following season.
Juanito soon left Madrid but remains a much loved figure around the Bernabeu, remembered in each game since his death in a car crash in 1992 aged just 37.
4. Iker vs. Ogro
After an 11 year gap, Bayern and Madrid played four times in four months during the 1999-2000 season. The Germans eased to a 4-2 win in late February's second group stage game at the Bernabeu, and teenage goalkeeper Iker Casillas was again left badly exposed in a 4-1 in the reverse in Munich.
"It's a bit risky to play an 18-year-old keeper," sniffed Bayern keeper Oliver Kahn, but the story was not over yet. Both teams progressed to the semifinals, where Nicolas Anelka scored early in the first leg as Madrid won 2-0. Kahn rushed from his goal to get involved in some late squabbles, and was greeted with more missiles from Madrid's Ultras on his return to his line. Anelka, 21, scored again in the second leg -- another reminder for the Bayern keeper to respect his youngers.
The teams met in both following seasons -- they were clearly the two best teams in Europe, and shared the trophy between them. Kahn got an interesting welcome on each visit to the Bernabeu and is still remembered as "El Ogro" around the Bernabeu.
5. Madrid's penalty woes
The wait for Madrid's "Decima" European Cup had stretched to 10 years when the teams met at the semifinal stage in 2012 and confidence surged as two Cristiano Ronaldo goals put Madrid 3-2 up on aggregate within the opening 14 minutes. Jose Mourinho's side then sat back and, with a young Toni Kroos impressing in midfield for Bayern, Arjen Robben's penalty evened things up before the half-hour mark.
It was tight and tense from then on, went to penalties. Manuel Neuer saved from Ronaldo and Kaka; Iker Casillas stopped efforts from Kroos and Phillip Lahm. The tension was too much for Sergio Ramos, who blazed his effort high over the crossbar, but not for Bastian Schweinsteiger, who calmly rolled in the clincher.
Ramos' miss became the butt of thousands of internet memes, with even Neuer joining in the fun by joking "I didn't know he liked to hit his penalties so high."
The Spain international then got his own back with a social media poke at Neuer when Chelsea beat Bayern on spot-kicks in that year's final. But the memories have never really gone away.