Roger Rasheed, former coach of Lleyton Hewitt, doesn't believe that having a third child would affect Hewitt's performance on the court.

The two-time major champion confirmed before the start of French Open that his wife is carrying their new baby.

Tennis is said to be a sport that hinders its players from becoming successful parents because of its physical, travel and mental demands.

Bec recently admitted that she and her husband had tried to put off having their third kid. Mia, their eldest who turns five in November, will start school next year.

"We were thinking we'd wait until Lleyton retires because travelling with two is plenty," she said.

Rasheed believes that the off-court distraction could be advantageous for Hewitt.

"To win a grand slam is a hard thing to do," Rasheed told AAP.

"Lleyton has won two and been a finalist in a couple of others and been very close in a lot of other championships.

"He knows what it is about and he knows what to do.

"Having kids, it brings him a lot of joy actually. It is a great down time thing. Instead of just being in your hotel you can spend time with your family."

This week at Roland Garros, Hewitt might have a third-round showdown with Rafael Nadal.

WIth his current world rank at number 28, he has to gain enough points to go up to the top 10 or 15 in the world.

It would not be easy for him to achieve his goals with three children and additional travelling, plus the lower body injuries that he has, coming from a hip operation.

Hewitt will go against Frenchman Jeremy Chardy on Tuesday and Rasheed thought it too early to say that Nadal won't meet Hewitt for the third round.

"I think that Rafa isn't probably excited about having Lleyton in the third round either as he is a champion player," he said.

"If Lleyton gets the chance to get through to the third round, which I hope he does, that is something he is going to really enjoy, being on the centre court and doing battle with Rafa."