Sparta Prague traveled to Belgrade with a comfortable 4-1 lead from the first leg against Partizan in the quarterfinals of the European Champions Cup in March 1966. High hopes accompanied the team, especially after a successful winter tour in South America. The media even expressed skepticism concerning Partizan's chances, firmly believing it would be impossible to overturn such a deficit. However, the return leg presented an unforeseen disaster for Sparta as they capitulated completely, losing 0-5, which led to their elimination from the tournament.

In stark contrast to their previous form, Sparta's performance in the second leg was abysmal. The team, who had been in prime condition heading into the match, displayed a striking lack of offensive and defensive cohesion. They failed to generate any meaningful scoring opportunities and left their goalkeeper facing relentless pressure from the Partizan attack. By the 35th minute of the match, the writing seemed to be on the wall for the Czech side, who could not muster a response nor find a way back into contention.

This shocking turnaround has fueled speculation and debate among fans and historians for decades, as many still seek to understand what went wrong that fateful day. The defeat has become a significant part of Czech football lore, often regarded as an inexplicable event that casts a long shadow over the history of the sport in the nation. The discussion around this legendary collapse continues, highlighting the unpredictability of football and leaving Spartan supporters and analysts pondering the mysteries that can arise in the world of sports.