In the game of football, many things can happen unexpectably, which can lead to a suprise win by a team and shock the world.
From unbelievable comebacks to shocking last minute goals, the actions of players can suprise many different people.
Throughout football history, their have been many different upsets that have suprised the world and here is a list of the 10 greatest upsets ever.
In the 2000 UEFA Cup, Chelsea expected to be a dominant team in the tournament, but were shocked by Swiss team St. Gallen in the first round of the tournament by a 2-1 score on aggregate.
Despite having a 1-0 lead after the first leg, Chelsea went into the Stadion Espenmoos in Switzerland and were shocked by two early goals by Sascha Muller and Charles Amoah as they weren't able to recover and lost the game by that score.
They also lost Roberto Di Matteo to a broken leg during the game, adding injury to insult.
In the round of 16 in the 2004 UEFA Champions League, Manchester United and FC Porto were paired together.
In the first leg at the Estádio do Dragão in Porto, Porto won 2-1 on two goals by Benni McCarthy, but Man United also had a goal by Quinton Fortune to give them an all important away goal.
In the second leg at Old Trafford in Manchester, Paul Scholes scored in the 32nd minute to give United the lead in the game 1-0 and on aggregate based on away goals.
But at the ending of the game, Costinha scored to give Porto a 3-2 win on aggregate over the English champions as Porto coach José Mourinho ran off the field celebrating as Porto went on to win the Champions League that season.
After being put into the Copa America in 2001 as an emergency replacement to Argentina, (who withdrew from the tournament after receiving death threats from a terrorist group), Honduras shocked the Brazilians in their opening match as they went on to beat the Brazilans 2-0 in their first ever win over the South American giant in their nation's history.
Even though they didn't win the tournament, this is considered to be the biggest upset for Honduras in their nation's history.
Going into the 1994 World Cup, Columbia was considered to be the favorite by many after not losing a game in World Cup qualifiers which included a suprising 5-0 win over Argentina in their final game before the tournament.
However, Columbia were stunned 3-1 by Romania in their opening game of the World Cup and then lost 2-1 to the United States to eliminate them from going onto the next round.
In their lost to the United States, defender Andrés Escobar scored an own goal, which sealed their fate in the tournament and Escobar was then murdered several days later in Columbia.
In the second round of qualifing in the 2005 UEFA Champions League, Scotish giant Celtic met Sloviarkan side Artmedia Bratislava-Petrzalka in what appeared to be a warmup for Celtic on their way into the Champions League that season.
But Artmedia didn't allow that to happen as they destroyed Celtic by a 5-0 score at the Tehelne Pole Stadium and Juraj Halenar had a hat trick for the home side, marking one of the worst games ever for Celtic in the Champions League.
Even though Celtic won the second leg by a 4-0 decision at Celtic Park, this wasn't enough as Artmedia won the series by a 5-4 win on aggregate on their way to qualifing in the Champions League that season.
In the opening game of the 2002 World Cup, Senegal (who was playing in their first ever World Cup game in their nation's history) played the French, who were the defending World Cup champions.
But despite some early chances by the French, Senegal never gave up and in the 30th minute, Pape Bouba Diop scored to give Senegal a 1-0 lead.
Afterwards, the French had several more good opportunities, but were denied by both the woodwork and keeper Tony Sylva as team Senegal won the game 1-0 over the French.
In 1992, team Denmark didn't even qualify to play in that year's Euro but were put into the tournament after Yugoslavia was broken into Serbia and Montenegro.
But after the two new countries were facing UN sanctions for war crimes from their war with Bosnia, UEFA had to act and forced the remaining parts of Yugoslavia to withdraw from the tournament and in came Denmark.
In the tournament, Denmark got great offensive play from Henrik Larsen and greak goalkeeping from Peter Schmeichel as Denmark beat the French, the Dutch (who were the defending European Champions), and the defending World Cup Champions team Germany as they won Euro 1992.
In the opening game of the 1990 World Cup, the defending World Cup champions Argentina were paired with Cameroon, who were in their first ever World Cup.
In that game, Andre Kana got sent off for Cameroon in the 54th minute of a scoreless contest, which insured that Argentina would win the game.
But Cameroon was resiliant as François Omam Biyik scored off a header in the 60th minute to give Cameroon the lead.
And despite going down to nine men at the end of the game, Cameroon won the game 1-0 and advanced all the way to the quarterfinals, where they were beaten in a memorable game by England.
During Euro 2004, their were many different European clubs that were challenging to become the champion, but the Greeks (with a 100-1 chance of winning the tournament) shocked the Portugese as they won the final 1-0 in Portugal to win the tournament.
After they scraped throught the groups stage, they were able to clean sheet the French and the Czech Republic on their way to the final in what turned out to be one of the best year's ever in Greek sports history (they also hosted the Summer Olympics that year).
In what is considered by many to be the greatest upset in World Cup history if not football history, the United States beat England 1-0 in the World Cup. In the beginning of the game, the English continued to take shot after shot, but American keeper Frank Borghi was equal to each opportunity.
Then in the 37th minute, Joe Gaetjens scored on a diving header to give the American's a 1-0 lead, which was the score in which the United States went on to win the game by.
This game is considered in the United States to be the Miracle on Grass and was in made into a 2005 movie called The Game of Their Lives.