Assignment 2: Second Alternative - Calculating Probabilities

To summerize from class, the problem can be defined as the following:
8 tennis players are about to go into a single-elimination knock-out tournament. A single-elimination knock-out tournament, is a tournament where whenever a player loses a game, that player is "knocked-out" of the tournaments. The games are arranged in a way, such that: A and B play together, and C and D play together. The winners from the matches play a third match. A more concise description can be found on wikipedia.
Each of the players is already assigned a different rank. The ranks are from 1 to 8, such that, rank #1 is the best player, rank #2 is the second-best player, ... and rank #8 is the worst player. Whenever two players play against each other, the player with the better rank always wins. Therefore, in our knock-out tournament, it is obvious that rank #1 is going to win the tournament.
The Problem: Given that the players are initially distributed into the knock-out tournament scheme, what is the probability that the players of rank 1 and 2 meet only at the final?