With a western or semi-western grip, the racquet strings point slightly toward the ground during the swing through towards the ball, at the precise moment of impact, the racquet is perpendicular to the ground, but continues to travel on the upward trajectory. This “brushing” upward on the back of the ball imparts top spin, which makes the ball drop into the court, and kick up higher after it bounces. Because the top-spin makes the ball drop into the court, you can hit the ball as hard as you want and still hit it in the court. This is not possible with a continental grip, where you are not hitting topspin. Note that if you are attacking and hitting down on the ball, the strings will point slightly towards the ground, and your swing trajectory will be different. This is just a basic demo of the topspin concept.
Here is Federer coming through in the same fashion.
On the slice, most people think it’s a real chopping down motion at the ball. They think the swing plane is downward, when in fact what you want to do is have a relatively flat swing plane with the angle of the racquet ever-so-slightly open, with the strings pointing slightly upward. This will impart backspin on the ball, but your flat swing-plane will make the slice cut through the court. If you chop down on the ball with a descending swing-plane, the ball will have backspin, but it will tend to float through the air slowly, and then stop with no pace when it bounces. This can be good if you want to feed your opponent a ball with no pace, but I would recommend practicing the knifing slice motion which is more aggressive and good for approach shots.
What do you think of when you’re hitting topspin or slice? Comment below!