Your opponents are not superhuman or godlike; they are humans, too. You need to understand that they get nervous just like you, they feel pressure and anxiousness just like you.
A ranked athlete or team may be afraid of losing there high ranking, or feel you might be the next best thing and the up and coming star. Try to understand that your competitors have weaknesses too and realize that other players are not perfect with their mental game.
In addition, I believe in the power of momentum, A team with a poor record can beat a winning team, a lower ranked athlete can beat higher rank athlete, when they have momentum and high confidence they find their comfort and start playing in the zone.
Everyone has good days and bad days during a competition or game, Remember that anything can happen. So staying positive and confident is a must, but if you don’t try your best you will never know what your potential is or where you rank as an athlete or team against the best.