A family of four, a father, a mother, a son and a daughter, play badminton doubles as two fixed teams of two. The following facts are known:

1. The father and the mother are not on the same team.

2. On whichever match is being discussed, the two players of the winning team are each individually a better player than each of the two players of the losing team.

3. The son's team lost the match.

4. The daughter is a better player than the son.

5. The father is a better player than the mother.

6. The father is a better player than the daughter.

Who is the best player among the four?