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The Logic of Hitting Topspin Groundstrokes Versus Flat Groundstrokes
By Tennis Tom©2003

Although hitting a tennis ball flat, with no spin, is initially simpler than hitting with intentional spin, it is far less effective in terms of consistency.

Hitting flat. Ignoring elements like the wind, etc., when you hit a ball it reacts according to two principal physical elements: the tilt (angle) of your racket face, and the swing path (direction) of your racket as it moves through the air. A flat racket face refers to the plane of the racket strings being more or less at a right angle with the flight of the incoming ball at contact. A flat swing path is a swing path which is more or less parallel with the court surface and which imparts little or no spin to the ball as it leaves the racket. (I use the phrase “more or less” because it is almost impossible to hit a ball with no spin at all.)

Notice that the ball approaches and leaves the racket face more or less at a right angle. The arrow to the left of the ball indicates that the ball eventually falls to the court surface by gravity.

The diagrams are for visualization purposes only. Actually few shots are hit perfectly parallel to the court surface. Most balls will approach you with an arc. Let’s hypothesize that a ball is approaching you at a 30 to 45-degree arc. If you tilt your racket face upward at the same angle to meet the oncoming ball, you are still hitting the ball flat, as both the racket face angle and the ball trajectory angle are the same. Even when you swing your racket from low to high, if the racket face hits the ball at a right angle then your are hitting the ball flat. Look at this diagram of another ball hit flat...

Note that the ball still approaches and leaves the racket face at the same angle. Almost no spin is on the ball as it leaves the racket.

What causes spin? Ball spin results from friction 1) when the racket strings hit the ball in any manner other than flat, 2) when the ball moves against the air, and 3) when the ball hits the court surface.

There are two broad types of spin:

  • Spin imparted to the ball when the racket face hits the ball other than flat (other than straight on), and
  • Spin which happens when the ball bounces off the court surface due to friction.

The types of spin imparted by the racket are:

  • Topspin – where the ball spins forward
  • Slice – where the ball spins backwards
  • Side spin – where the ball spins either to the left or to the right
  • Combination spin – where the ball is hit with a combination of sidespin and topspin, or a combination of sidespin and slice – both are advanced shots which will not be elaborated in this discussion

Your racket movement (swing direction) for each primary spin shot is:

  • Topspin – racket moves from a low position to a high position as you hit the ball
  • Underspin / slice – racket moves from a high position to a low position as you hit the ball
  • Side spin – racket moves right to left for spin to the right; vice versa for left spin

TOPSPIN. To hit a topspin stroke the racket face should be on edge approximately straight up and down, or put another way, perpendicular to the court. The forward spin comes from the low to high upward motion of the forward path of the racket. Brushing up the back of the ball when the racket meets the ball causes topspin.

Due to the upward path of the racket, the face brushes up the back side of the ball, causing the ball to fall in an accelerated downward arc toward the court with topspin.

FOOTWORK. You may find as a learner that your natural tendency is to be too close to the incoming ball after it bounces. The way to correct this is to watch the ball intently, learn to gauge the ball’s flight by trial and error, and move backward when the ball is coming in too high. In tennis the backward, sideways, and forward adjustment of your body is called “footwork.” Your footwork will become better in the unfolding of time. (What a yummy phrase!) How to hit incoming balls that are shoulder high or higher is a more advanced maneuver and will not be covered here. If you have time, the best way to address a high incoming ball is to back up a few feet and let the ball fall to your waist level, i.e. to your “hitting zone,” and then hit a topspin groundstroke.

SLICE. The other major type of spin is underspin or slice. Slice can be hit on your forehand or your backhand side. To hit underspin you need to adjust the tilt of your racket face to an more open angle. Start your downward swing from a point somewhere near your neck level and move the racket forward from high to low. It takes experimentation with the racket face angle to get it right. Typically learners tend to open the face way too much and the result is a moonball, in other words a high lob.

Lob, definition. A lob is a ball hit so that it goes high in the air above the heads of the opponents and is intended to land in the opponents’ backcourt. A lob is often used in a defensive situation. If hit properly it allows you time to get out of trouble and get into a good court position before your opponent can return your ball. Oh yes, it you accidentally hit your lob so low that their net person can smash it, be prepared to eat a tennis ball sandwich.

SIDE SPIN. Finally, the third type of spin is side spin, which is an advanced stroke and will be covered elsewhere.

CLOSED RACKET FACE and OPEN RACKET FACE definitions. To close your racket face means to tilt the top of the face downward, so that the face is pointed more toward the court surface. To open your racket face means to tilt the top of the face backward, so that the face is pointed more toward the sky. Learners often tend to hit the ball with their racket face too open which results in the ball going very high or out of the court past the opposite boundary line altogether. When this happens on court you will hear the words, “Close your racket face.” Generally this instruction means to adjust your racket face so that it is straight up and down (vertical) rather than open (tilted toward the sky).

Your HITTING ZONE definition. Your best ball striking zone (or window) to contact the ball for a groundstroke, is somewhere between your knee level and your lower-chest level. One of the constant challenges to players at all levels is to move their body quickly to a spot where they can set up and contact the ball in their hitting zone. If you don’t get to the right spot before the ball reaches you, your shot will not be dependable. And tennis success is mainly about consistency rather than power.

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I teach spin for both the forehand and the backhand groundstrokes to all students. One of my favorite beginner students, Karen J., used to drive me crazy with her questions. The first time I gave her any particular instruction she invariably asked, “Why is that?” So, to address the question of why to hit topspin, the following...

When you swing “flat,” that is to say, when you contact the ball with a more or less flat racket face and a more or less flat swing, (not including a lob), you have to be VERY accurate with the racket face in order to get the ball over the net and in the court with any significant pace (speed). Hitting the ball hard with a flat swing exponentially compounds the problem of accuracy, as you will understand from reading the next four paragraphs.

Consider the following example which was done scientifically with a mechanical hitting arm per Vic Braden, a world class tennis teacher. When a ball is hit flat from one baseline to an area somewhere in the opposite backcourt, with the racket face at a certain angle the ball lands at a certain spot. If you hit a second ball in the same manner and with the same speed, but with the racket face having ONE DEGREE difference of upward angle, the ball will land about 6 FEET FURTHER in the court. That’s a huge difference.

Flat (no spin) versus topspin on groundstrokes. The first major factor when you hit flat (ignoring the wind) is that the only thing you have to bring the ball down into the court is gravity. When you hit topspin you not only have gravity to bring the ball down but also significant air friction on the top of the spinning ball (in conjunction with the lower air friction on the bottom of the ball) which causes the ball to have a much sharper downward arc toward the court. In real life this means that when you hit with pace and topspin the ball falls into the court more often.

The second significant factor is that when you hit flat, if you hit with medium-hard or harder pace, (other than a lob), you are compelled to hit the ball relatively close to the top of the net. Otherwise the ball will fly out past the opposite baseline and you’ve lost the point. If you visualize the distance between the net cord and the highest point at which the ball can travel without going past the baseline, or into the net, you have a window of possibility through which the flat ball must travel to stay in the court. Depending on the speed of the flat ball – at medium hard pace - let’s estimate that you have a window about 18 inches high or less. Your window of possibility then is between the top of the net and a point a foot and a half above the net. If you hit a pacey ball a little too high above the window, the ball flies out; if hit a little too low, the ball hits the net. So, when you hit flat you have very little room for error with your racket face. On the other hand, when you hit the ball with topspin you double or triple your window of possibility! This is the reason that better/experienced tennis players hit groundstrokes with topspin. They have learned that they have more control when hitting topspin, and they can hit a more aggressive shot if they so choose.

A third factor is that a flat ball bounces with very little spin when it hits the court, which means that the opponent, having more time to judge the ball, finds a flat hit ball easier to return. Conversely, a ball hit with topspin kicks forward and up when it contacts the court and decreases an opponent’s available reaction time. The more spin the topspin ball has, the less reaction time the opponent has. The topspin bounce thusly requires an opponent to have better timing and better footwork in order to contact oncoming topspin balls in their hitting zone.

In the vast majority of circumstances hitting spin on your groundstrokes, whether it’s topspin or slice, is far superior to hitting flat and will stand you in good stead for the rest of your tennis playing life. Spin should be your friend.


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