Who has been the biggest upset or surprise team in the World Cup so far?

The question of which team has been the biggest surprise depends heavily on which World Cup tournament we are discussing, but looking at recent history and notable upsets, a few teams stand out as truly shocking stories that captured global attention. In the 2022 World Cup in Qatar, Saudi Arabia produced arguably the single most shocking result in recent World Cup history when they defeated Argentina 2-1 in the group stage. Argentina entered that tournament as one of the heavy favorites, riding a 36-match unbeaten streak and featuring Lionel Messi in what was expected to be his final World Cup. Saudi Arabia came back from a goal down and scored twice in the second half to stun the football world. The win was celebrated as a national holiday in Saudi Arabia, and the image of Messi and his teammates sitting in stunned silence in the locker room circulated everywhere. Despite that incredible result, Saudi Arabia did not advance past the group stage, which somewhat limited their overall impact on the tournament narrative. However, if we are talking about a team that sustained their surprising run throughout an entire tournament, Morocco in 2022 stands as perhaps the greatest overachieving story in World Cup history. The Atlas Lions became the first African and Arab nation to ever reach the semifinal of a World Cup. They knocked out Belgium, Spain, and Portugal along the way, with their defensive organization and passionate performances captivating fans worldwide. Their goalkeeper Yassine Bounou was exceptional, and the team played with incredible unity and tactical discipline under coach Walid Regragui. The scenes of Moroccan players celebrating with their mothers on the pitch became iconic images of that tournament. They eventually lost to France in the semifinals but finished fourth overall after defeating Croatia in the third-place match, cementing their place in football history. Going back further, South Korea in 2002 remains one of the most controversial and stunning runs in World Cup history. Co-hosting the tournament with Japan, South Korea reached the semifinals by defeating Portugal, Spain, and Germany. Their run was celebrated enormously across Asia but was also accompanied by significant controversy, as several refereeing decisions in their favor drew criticism from eliminated teams. Still, the passion and energy they generated, combined with the coaching of Guus Hiddink, made them a phenomenon that tournament. Senegal in 2002 also deserves mention, as they defeated defending champion France in their opening match and went on to reach the quarterfinals in their very first World Cup appearance. That team featured players like El Hadji Diouf and Papa Bouba Diop and announced African football to the world in a powerful way. Similarly, Cameroon in 1990 shocked Argentina in the opening match and reached the quarterfinals, becoming a beloved story of that tournament. If the question refers to an ongoing or current tournament, the answer would depend on the specific competition taking place at the time of asking, but based on the pattern of recent World Cups, it is the combination of a single jaw-dropping result like Saudi Arabia over Argentina and a sustained run like Morocco's that together define what we mean by a surprise team. Morocco's achievement is likely the most complete and historically significant surprise story in modern World Cup football, combining tactical excellence, emotional resonance, and genuine historical milestones in a way that no other underdog team has quite matched in the modern era of the tournament.