John McEnroe, former World No. 1 professional tennis player from the United States, declared he's disappointed by Venus and Serena Williams performance, arguing their extra-curricular interests harm them.

The Williams sisters have been a force in the sport for a number of years, but because of their other interests, they haven't trained as hard and they seem to be designing clothes and wanting to be an actor or actress.

He says, "It's a little disappointing to see them, because this story is probably unheard of in sports in general: two sisters become (numbers) one and two in the world.

"I don't blame 'em for getting bored at times. They seem to be so much better. But they haven't trained as hard and they seem to be designing clothes and wanting to be an actor or actress and it seems like their focus has left.

"What happens is they're not around the tennis as much, so that ends up hurting the sport."