Question: FK Partizan is a professional football club based in Belgrade, Serbia, and became the first Eastern European club to play in the European Cup final, losing by Real Madrid in which 1966 football match held at the Heysel Stadium, Brussels?

Context paragraphs:
1985 European Cup Final: The 1985 European Cup Final was a football match between Liverpool of England and Juventus of Italy on 29 May 1985 at the Heysel Stadium, Brussels, Belgium.  It was the final match of the 1984–85 season of the European Cup, Europe's premier cup competition.  Liverpool were the reigning champions and were appearing in their fifth final, having won the competition in 1977, 1978, 1981 and 1984.  Juventus were appearing in their third European Cup final; they had lost their two previous appearances in 1973 and 1983.

Football in Serbia: Football is the most popular sport in Serbia.  The Football Association of Serbia ("FSS") is the national governing body and is responsible for overseeing all aspects of the game of football in the country, both professional and amateur.  The association organizes the professional Serbian Superliga (top tier) and is responsible for appointing the management of the men's, women's and youth national football teams in Serbia.  The association also organizes the Serbian First League (second) and Serbian League (third), operating the top 3 leagues.  The FSS is also responsible for organizing the Serbian Cup, the country's league cup competition.  It has been played from the end of the 19th century and there were a number of very successful Serbian football players and coaches throughout history.  One of Serbia's top football clubs Red Star Belgrade has won the prestigious European Champions Cup in 1991 and has also won the Intercontinental Cup the same year.  Its local rival Partizan Belgrade was the first Southeast and Eastern European football club to reach the European Champions Cup final, when it did so in 1966.  The most successful and popular teams are Red Star and Partizan from Belgrade as well as Vojvodina from Novi Sad.  An important role also played OFK Belgrade and Radnički Niš in the history of the Serbian football

Milovan Ćirić: Milovan Ćirić (12 February 1918 – 14 October 1986) was a Serbian football coach and former player.  He was the first captain of Red Star Belgrade (1946–1947) but in June 1947, he moved to city rivals FK Partizan (1947–1948).  With FK Partizan he won Yugoslav cup (1947).  After finished his career as a player, Ćirić first worked as a coach in FK Partizan (1948–1951) as youth team manager.

1976 European Cup Winners' Cup Final: The 1976 European Cup Winners' Cup Final was a football match between West Ham United of England and Anderlecht of Belgium.  The final was held at Heysel Stadium in Brussels on 5 May 1976.  It was the final match of the 1975–76 European Cup Winners' Cup tournament and the 16th European Cup Winners' Cup Final.

1966 European Cup Final: The 1966 European Cup Final was a football match held at the Heysel Stadium, Brussels, on 11 May 1966 that saw Real Madrid of Spain defeat Partizan of Yugoslavia 2–1.

1985 European Cup Winners' Cup Final: The 1985 European Cup Winners' Cup Final was a football match contested between Everton of England and Rapid Wien of Austria.  It was the final match of the 1984–85 European Cup Winners' Cup and the 25th European Cup Winners' Cup Final.  The final was held at Feijenoord Stadion in Rotterdam, Netherlands, on 15 May 1985.  Everton, which dominated throughout, won the match 3–1 thanks to goals by Andy Gray, Trevor Steven and Kevin Sheedy.  Everton were unable to defend the trophy: as league champions they would have entered the 1985–86 European Cup, but they were not permitted to play in either competition following the actions of rival Liverpool fans at the Heysel Stadium, which saw all English clubs banned from European competitions.

FK Partizan in European football: FK Partizan is a professional football club based in Belgrade, Serbia.  Founded in 1945, they were the first Yugoslav and Serbian club ever to enter European competition, playing the European Cup in the 1955–56 season.  They opened the competition in a match against Sporting Clube de Portugal on 4 September 1955.  They also became the first Eastern European club to play in the European Cup final, losing by Real Madrid in 1966.

1958 European Cup Final: The 1958 European Cup Final was a football match which took place at Heysel Stadium in Brussels, Belgium on 28 May 1958.  It was contested by Real Madrid of Spain and Milan of Italy.  Real Madrid won 3–2 after extra time to claim their third European Cup in a row.

FK Partizan: Partizan was founded by young high officers of the Yugoslav People's Army (JNA) in 1945 in Belgrade, as part of the Yugoslav Sports Association Partizan.  Their home ground is the Partizan Stadium in Belgrade, where they have played since 1949.  Partizan holds records such as playing in the first European Champions Cup match in 1955, as well as becoming the first Balkan and Eastern European football club to reach the European Champions Cup final, when it did so in 1966.  Partizan is the first and only Serbian club to compete in the group stage of the UEFA Champions League.

1980 European Cup Winners' Cup Final: The 1980 European Cup Winners' Cup Final was a football match contested on 14 May 1980 between Valencia of Spain and Arsenal of England.  The final was held at Heysel Stadium in Brussels, Belgium.  Valencia won the match 5–4 on penalties.  It was the 20th European Cup Winners' Cup Final and the only time that the winner of the tournament was decided by a penalty shootout.

Supporting paragraphs: FK Partizan in European football 1966 European Cup Final
Answer: 1966 European Cup Final