Ethnically motivated violent pitch invasion

The season featured a huge politically and ethnically motivated incident during the Hajduk Split vs. FK Partizan tie on Wednesday, 26 September 1990 at Poljud Stadium, when a mob of hardcore Hajduk fans invaded the pitch during second half in an attempt to lynch Partizan players. All of the Partizan players managed to run away into the dressing room, thus escaping unharmed. While chanting anti-Serb slogans, the violent mob then set fire to the Yugoslav flag that was displayed on the stadium's official mast. They then proceeded to raise the Croatian chequerboard flag (at the time not in official use and thus considered a Croatian nationalist symbol). At the moment of the incident, Partizan was leading 0-2 courtesy of a Milan Đurđević brace. The match was never resumed and eventually registered 0–3 in Partizan's favour.

Eternal derby: Red Star v. Partizan incidents

On Saturday, 27 April 1991, only three days after making the European Cup final by advancing against favoured Bayern Munich via managing a hard-fought home draw in the famous emotional rollercoaster semifinal return leg in front of 90,000 fans, league leaders Red Star hosted their heated cross-town rival FK Partizan in the 88th league edition of the Eternal derby. Following an entertaining first half played in front of some 35,000 spectators, at the end of which Red Star led 3–1, the match was halted for 10 minutes at the beginning of the second half due to FK Partizan ultras, the Grobari, rioting in the Marakana stadium's south stand by pelting the pitch and athletic track with construction material found in front of the stand.

The match play resumed before being interrupted several more times throughout the second half due to Partizan ultras continuing to riot despite increased police presence around the south stand and even, at one point, pleas of the team's striker Predrag Mijatović sent by the head coach Miloš Milutinović in an attempt of calming them. The match ended 3-1 for Red Star.

Dinamo v. Red Star match-fixing allegations

On Saturday, 18 May 1991, Dinamo Zagreb hosted champions-elect Red Star Belgrade at Maksimir Stadium. The match was of no competitive importance since Red Star had already clinched the league title as it prepared to travel to Bari for the European Cup Final some ten days later while Dinamo had cemented its hold on the second place that ensured a UEFA Cup spot. However, the match still carried a degree of tension due to pitting a marquee Croatian side versus a marquee Serbian at a time when ethnic conflicts, some of them deadly, had started taking place in the Socialist Republic of Croatia, and especially in light of the fact this was the first time the two teams met at Maksimir following the previous season's Dinamo–Red Star riot in the stands, with that match being called off.

This time the match began as scheduled and finished without interruption with Red Star going 0–2 in front before Dinamo mounted a spirited come-back for a 3–2 win at full time. However, more than 20 years later, allegations appeared that the contest had been fixed via confessions from two of the match's protagonists.

Speaking to Globus magazine in September 2012, Robert Prosinečki, Red Star midfielder back in 1991, said his team "let Dinamo win that day".^[1][2]

Prompted by Prosinečki's claims, Ljupko Petrović, Red Star's head coach in 1991, expanded: "We didn't lose that match by arranging with someone from Dinamo beforehand to let them win. No. We were simply forced into losing by the political circles that wanted to ensure Dinamo's win that day. The war had practically already begun, Croatia was about to declare independence, and the match was taking place only a year after the previous incident when Zvonimir Boban assaulted a policeman—our first away match versus Dinamo since then. I remember Franjo Tuđman being at the match and watching it from the luxury box with his cronies and the overall atmosphere within the stadium being extremely hostile such that no result but Dinamo's win was going to be acceptable. We got up 0-2, but towards the end of the first half Dinamo got a penalty on a scandalous and very obvious dive by Davor Šuker. Later, they managed to tie the score. At halftime I protested vehemently with the referee, a Montenegrin guy whose name I can't recall at the moment, and from what he told me it was apparent between the lines that it had already been decided we had to lose that match for political reasons. Because Tuđman is sitting in the stands and because he doesn't want a Serbian team winning in the middle of Zagreb right in front of his eyes at a time when he's creating an independent state. I got thrown out of the match, we conceded once more, we lost the match and that's the whole story".^[3]