There is no way to answer this question, because many factors are involved, including, primarily, ranking and emotional fervor over the players, and the score (e.g., the 128th seeded player defeated the #1 seed; or a total unknown defeated the most popular or #1 seed; or the score of a match was 6-0, 6-0, 6-0). Plus the fact that many of the older matches were not recorded in full by history, so little may be known about one or both of the opponents (i.e., a truly momentous "upset" may have been lost to time). If you were to search the web for the answer to this question, you might find many such answers (n.b., on one such search, I found SEVEN possible and completely different, answers, though some may have been prejudiced, because they were fan or country-specific sites).
Mexico 1986
Ole Miss over Texas Tech 2009
Not winning the worldcup
well it depends really its not that nice to have a biggest fan because it makes all the other people angry and upset
well it depends really its not that nice to have a biggest fan because it makes all the other people angry and upset
1980's USA win over the USSR went on to be known as the "miracle on ice" because nobody had ever beaten the Soviets before
Joe Namath is a Hall of Famer because he lead the New york Jets to a huge upset of the Baltimore Colts in Superbowl 3. Some consider it to be the biggest upset of all time.
Actually Wimbledon does not play as it is not a person.The tennis players only play in the Wimbledon championship in the All England Club which was in Wimbledon district.
The All England Club hosts Wimbledon.
The biggest merger of all time is the America Online and Time Warner merger. The merger is valued at $186.2 billion dollars.
The Championships, Wimbledon are played at the All England Club in the suburb of Wimbledon (Greater London). It is the oldest tennis tournament in the world, dating to 1877.
Elton John's "Candle In The Wind" overtook Bing Crosby's "White Christmas", as the all-time biggest selling single of all time, in 1999.