The Dallas Cowboys are one of the biggest franchises not just in the NFL but in the entire sporting world. They have also proven that they are indeed “America's Team,” being almost a staple in the postseason with 33 playoff appearances since joining the league in the 1960s.

Their five Super Bowl crowns are merely icing on top of owner Jerry Jones' cake of success. It hasn't always been great for the Cowboys though, and they have hit some huge bumps along the way.

Let's take a look back at some key defeats and heartbreaks in the Cowboys' decorated history.

1981 NFC Championship vs The San Francisco 49ers

One of the earlier heartbreaking moments of the Cowboys was in the 1981 NFL playoffs. After winning the division championship in the regular season, the Cowboys entered the postseason as the second seed and went on to blowout Tampa Bay in the first round. Their next match wasn't going to be a walk in the park, as they were set to meet the first-seeded San Francisco 49ers in Candlestick Park, San Francisco.

Things looked good for the Cowboys as quarterback Danny White led the Texas-based squad to mount a 27-21 lead late in the game. This was where lady luck started to turn to the home squad. With 58 seconds on the clock, 49ers QB Joe Montana managed to earn his team a 3rd-and 3 at the Cowboys' 6-yard line.

Montana called the fabled “Red Right Tight-Sprint Right” play which opened the door for wide receiver Dwight Clark to make an unforgettable grab and write his name in the record books. “The Catch,” — which went down as one of the most historic plays in NFL history — completed the 49ers' comeback and sealed the 28-27 win against the Cowboys.

The loss ended a decade-long domination of the Cowboys and practically passed the NFC torch to the 49ers who then built a dynasty in the 1980s.

Joe Montana, 49ers

2007 playoffs vs The New York Giants

2007 was an incredible year for the Cowboys. They had one of the more successful runs in recent history, snagging 13 wins to match their franchise record and finding themselves sitting pretty as the top seed of the NFC.

The Cowboys looked awfully confident coming in to the second round of the playoffs since they were going to go up against their NFC East rivals, the New York Giants — a team they've already met and beaten twice in the regular season. QB Tony Romo and other members of the Cowboys decided to fly off to Cabo San Lucas to let off some steam and take a much-deserved few days off.

Looking good for the Cowboys so far, right? Well, Eli Manning had a different plan.

Fresh from their week off, the Cowboys seemed a bit rusty as the Giants came out swinging and immediately scored with a 52-yard touchdown from Manning to wide receiver Amani Toomer. Romo (who was probably sporting a sick tan) didn't back down as the contest was tied at 14 at the half.

After grabbing the lead in the third quarter, the Cowboys were looking at a 4-point deficit early in the last quarter. Dallas wasn't out yet, as Romo was presented with two more opportunities to win the game in the dying moments of the match. Unfortunately, an incomplete pass to receiver Patrick Crayton was followed by an intercepted heave deep in the end zone which ultimately spelled the game and the season for the Dallas franchise.

The Giants got the 21-17 upset win over the Cowboys and eventually went on to continue their magical run to Super Bowl XLII where they were crowned champions after beating the undefeated New England Patriots.

Tony Romo

2016 playoffs vs The Green Bay Packers

After a pre-season injury sidelined Tony Romo for much of the season, Dak Prescott took over the signal-calling duties. The rookie didn't take long to impress as he led the Cowboys to an 11-game winning streak after dropping their season opener against the Giants.

Prescott went on to tie an NFL record by throwing multiple TDs in five straight games in that stretch. The young QB, alongside stellar rookie Ezekiel Elliot, led the way for the Cowboys as they ended another triumphant regular season with the NFC East title and the home field advantage in the upcoming playoffs.

The Green Bay Packers were up next. Despite having the top seed in the division and also playing at home, the Cowboys struggled early on as Aaron Rodgers and the Packers seemed to have controlled the first three quarters of the game. Green Bay entered the 4th with a 28-13 lead over Dallas.

Aaron Rodgers, Packers

Prescott rallied his troops and valiantly fought back to tie the game at 28 with four minutes to go in the match. A Mason Crosby field goal for the Packers was cancelled out by Dan Bailey's, which again tied the game at 31 with just 35 seconds left. The Packers' kick-taker was given one last shot as Rodgers brought them into FG range.

With three seconds in the clock, Crosby rocketed a 51-yard field goal to break the hearts of the Cowboys.