 Complete the following phrase:  In most professional tennis matches, a tiebreaker rule applies in each set to avoid lengthy matches, as happens quite frequently if the traditional tennis rule for winning a set is followed. When players reach a score of 66 in a set, instead of continuing the set until one opponent wins with a two-game difference, a special game is played to decide the winner of the set; the winner is the first to reach at least seven points with a difference of two over the opponent. This however does not apply to the final set of matches at the French Open, allowing the total number of games in a match to be virtually unlimited for example, the final set of the 