De Klassieker (The Classic) is the main football rivalry of the Netherlands, between Ajax (of Amsterdam) and Feyenoord (of Rotterdam).
[5] The inhabitants of these cities differ significantly in both attitudes and cultures which is clearly reflected on the football pitch.
Ajax’s style of play has long been a source of pride for the supporters, and one of irritation for the Feyenoord fans.
A harbor town, its people are proud of their work ethic and resentful of Amsterdam's showiness.
This was later officially declared 2–2 due to Feyenoords protest to what they believed was a dubious goal by Ajax.
The status of the Olympic Stadium being the largest in Netherlands would change in 1937 when Feyenoord opened De Kuip was constructed with a capacity of 64,000.
This was due to Feyenoord never winning their regional league in this period and hence not reaching the Championship Playoff where they could face Ajax.
[10] This rivalry heated up considerably in the early 1970s when these two clubs were arguably the best in the world and riots started to break between the sets of fans.
[11][12] This success led to the Netherlands squad being filled with a majority of Ajax and Feyenoord players.
Many fans would also whistle and jeer at the newcomer during the friendly pre season games and whenever his name was announced in the stadium.
[15] Both clubs have fallen from grace over the years, while fan violence has increased, and there is always a heavy police presence at the derby.
The most serious incident occurred in the Beverwijk clash in 1997 when Ajax fan Carlo Picornie was killed and several others injured.
One Ajax fan, Carlo Picornie, was beaten to death by rival supporters, triggering more strict policies from the Dutch football association KNVB to tackle hooliganism.
In February 2009, the mayors of Amsterdam and Rotterdam made an agreement with the KNVB to ban visiting fans from the away games for the next five seasons in an effort to curb the violence.
Ajax hooligans planned a revenge attack on Feyenoord fans but were stopped by police.
[28] Later in the same month, there was an incident during the U19 league title deciding game between Ajax and Feyenoord at De Toekomst in Amsterdam.
After 30 minutes, the match had to be suspended due to Ajax fans trying to attack the Feyenoord players' families in the stands.
[29] On 5 April 2023, during a KNVB Cup semifinal, Ajax player Davy Klaassen was hit with a lighter from the stands during the 62nd minute of the game.
[30] The match between the clubs on 24 September 2023 was suspended until further notice after Ajax fans, with Feyenoord winning 3–0, threw flares onto the pitch.