Have you thought of taking photos yourself?
You can try searching "Free clip art: tennis" - you may not find photos but you'll at least find totally free tennis graphics.
Since June 10, 2012 a vegan aarf but still writing the Hound Dawg Sports Blog
"If you don't have time to do it right, when will you have time to do it over?" -John Wooden;
"Governor, we also have fewer horses and bayonets" -Pres. Barack Obama