Not get dehydrated

Non-stop pounding around a tennis court dehydrates you very fast: you lose around a litre an hour when you're playing, especially if it's hot and windy. Dehydration is bad for your health and can cause sickness, intestinal problems, headaches and heatstroke, as well as affecting your performance on court. 

To stay hydrated, it's essential that you take on plenty of fluids regularly:
-Before your game: Drink a large glass of still water or diluted fruit juice an hour and a half before your game and another one an hour before you play.
-During your game: Every time you change sides (roughly every 10 - 15 minutes), get into the habit of drinking about a glasssful of water in small sips. 
-After your game: Immediately after your game and during your warm-down and stretch, take on 3 glasses of still water - preferably mineral water to replenish the minerals you've used up during exercise.