The most important nutrient a player needs is water!
You can go weeks and even months without certain vitamins or minerals before noticing an effect, but without adequate water, performance can be affected in less than an hour.
Water is necessary for your body’s cooling system. It also transports nutrients throughout your tissues and maintains adequate blood volume.
If you wait until you are thirsty to drink, you have waited too long. It is important to make a conscious effort to drink before you get thirsty.
In hot and humid weather, athletes can sweat off 6 pounds per hour. Each pound of weight lost as sweat is equal to two cups of water.
Two hours before a match in hot weather, you should drink 20 ounces (600ml) of fluid in addition to four to eight ounces (120-240ml) of chilled water every changeover.
The game of tennis provides an excellent opportunity for regular hydration during the odd game changeover; so take our word for it: “just do it” and you'll play better for longer.