You see this in sporting events quite often. Team A gets off to an early lead and victory seems inevitable.
But then something strange starts to happen. Team A is no longer playing as the dominant team. They begin to play like they have never even seen the sport on television. Team B then begins to gain momentum and closes the gap of victory. Team B now looks like the dominant team. Soon after they tie the game, they take the lead, and win.
We all have fallen into the trap of thinking that things are better than they really are or worse than they appear to be.
Be hopeful in times of perceived defeat and humble in times of perceived victory.
A good coach will remind his/her team, when leading, to continue to play with the same tenacity that got them the large lead. Play to win the game, don't play to not lose.