Anna Kournikova is pregnant.

The former tennis player - who has two-year-old twins, Lucy and Nicholas with long-term partner Enrique Iglesias - is set to welcome her third child into the world in the coming months.

The couple haven't commented on their happy news, but pictures obtained by Spain's Hola! magazine showed the pair on a boat in Miami, with the 38-year-old star's huge bump clear to see.

It is no surprise the pair have kept Anna's pregnancy under wraps as they didn't reveal they were expecting their twins until days after the tots were born.

The 'Hero' singer previously admitted he hopes he's a ''cool'' dad but also felt he'd developed a new sense of responsibility since welcoming his twins into the world.

He said: ''It's one of the best feelings in the world. [I'm more responsible]. I drive slower. I think about stupid things a few more times before doing them.

''I hope to be a cool, easy-going dad.''

Enrique has kept his personal life - including his relationship with Anna - out of the spotlight for many years and he previously admitted he doesn't think ''perfect relationships'' exist as there can be ''bad times'' between every couple.

He shared: ''You go through your good times, you go through your bad times. It's a tough thing for me to believe there's such a thing as the perfect relationship. I don't think that exists ...

''Firstly, she's the coolest girl in the world. And she understands who I am, to the point where she's willing to sacrifice her personal time with me and let me do my music. It's a huge sacrifice and I respect that tremendously.''