Ok, time to toss in a little American baseball.
How about the 2004 American League Championship Series between the Boston Red Sox and the New York Yankees....whom are bitter, bitter rivals (people have been shot in both Boston and New York for wearing the wrong team's hat).
Anyways, the ALCS is a best of seven series and the Red Sox went down to the Yankees 3 games to none. No team has ever come back from a 3-0 deficet. Well....man....brings back good memories and is WAY too much to recount here but the Sox tie it up in the bottom of the 9th inning at 4-4 at Fenway park thanks to Kevin Millar hitting a single and then Terry Francona pinch running Dave Roberts who stole 2nd base in what is probably the most famous steal of all time and then Bill Mueller brought him home with a single to tie it up. Long story short, the Red Sox win it in 12 innings, go on to beat the Evil Empire in 7 games and swept the St. Louis Cardinals in the World Series 4 games to none.
This is considered by many to be the greatest come back ever and is especially sweet once you realize the Sox hadn't won a WS in 86 years.
(the following year, 2005, the other sox, Chicago White Sox would take their first World Series Championship in 88 years, two historic seasons back to back)