9. The Match of Giants. Kafelnikov won one set against Becker with a score of 6:3. In five games, the player who served won. Who served in the first game?
9. The tennis player who served in the first game served five times. Let's say Kafelnikov won $x$ games out of these five and $y$ games out of the remaining four. Then, the total number of games in which the serving side lost is: $5-x+y=5$ (since according to the problem, in five games, the server won). Therefore, $x=y$, and the one who won the first game won $2x$ games. This means Kafelnikov served first.