It should come as little surprise that winning the first round gives you an advantage as the game continues. You are already more likely to win the second round, and if you do your advantage is further increased.
It is however by no means a foregone conclusion. Examining all of the possibilities the probability of the winner of the first round going on to win works out at about 63.5%, with the chance of the initial underdog seeing a reversal of fortune as the remaining 36.5%.
The exact values, should you be interested, are as follows:
Initial winner winning: 137009/215622
Initial loser winning: 78613/215622
The most likely specific sequence of results by a long way is for the initial winner to simply win every round. This occurs with a probability of 3315/10648 or just over 31% and so alone accounts for almost half of the initial winner’s possible routes to victory.