Winning a point is a very low bar. You donāt have to beat her. You donāt have to win a set or a game. You just have to score a single point. All it takes is a single mistake from your opponent to win a point. With enough time even the best will make a mistake, and tennis matches are long.
The shortest possible game is 4 points. A set without a tie breaker has 6 games. A womenās tournament match is best 2 sets of 3. So at minimum a match of tennis has 48 points. You only need one.
If youāre passible enough to return the ball some of the time, and do a valid serve you will probably win a point at some point. She may be one of the best tennis players of all time, but sheās not infallible. Its really unlikely she wouldnāt mess up at least once.
The survey is specifying one game though, not a set or a tournament. I donāt know the rules of tennis, but i donāt think Serena will let a single point through.