World Cup Fans -- Roller Coasters Of Emotion!

The World Cup is a HUGE deal -- the most watched event in sports next to the Olympics -- which explains why fans are on pins and needles watching the tournament!!

There have been a mixture of easy wins, upsets and close contests throughout the matches so far ... and understandably, all the backers have let their emotions out while cheering on their beloved teams in the stands.

Japan fans were glued to their seats and TVs as they watched their team pull off a stunning 2-1 upset over World Cup favorite Spain ... cementing their spot in the round of 16.

However, that wasn't the case for fans of Iran ... who were teary-eyed after watching their guys fall to the United States.

South Korea punched its ticket to the knockout stage for the first time since 2010 after defeating Portugal 2-1, and its fans were visibly emotional following the big win.