The top 10 biggest international sports events in 2021 are:
1. Summer Olympic Games (Tokyo, Japan)
2. UEFA European Championship (Euro 2020 postponed to 2021)
3. Wimbledon Tennis Championships (London, United Kingdom)
4. Tour de France (France)
5. ICC T20 World Cup (India)
6. Copa America (South America)
7. Rugby League World Cup (England)
8. Formula One World Championship (Various locations)
9. The Masters Golf Tournament (Augusta, United States)
10. UEFA Champions League Final (Istanbul, Turkey)
Please note that these events are subject to change or cancellation depending on the ongoing COVID-19 pandemic and any associated restrictions.