Serena Williams went public, as she took to Instagram to give a stinging reply to Nastase.

"It disappoints me to know we live in a society where people like Ilie Nastase can make such racist comments towards myself and unborn child, and sexist comments against my peers," Williams wrote on her social media account, on Monday.

"I am not afraid unlike you. You see, I am no coward."

The comments come after Nastase, who is Romania's Fed Cup captain, was heard commenting on Serena unborn baby saying: "Let's see what colour it (the baby) has. Chocolate with milk?"

The comments didn’t sit well with the ITF, and has been provisionally banned from all ITF events following his verbal abuse of British players last weekend in his role as Romanian Fed Cup captain.

"The ITF does not tolerate discriminatory and offensive language and behaviour of any kind," the governing body for tennis said in a statement to AFP.

"We are aware of alleged comments made by Romanian captain Ilie Nastase and have begun an immediate investigation so that we have the full facts of the situation before taking further and appropriate action," the ITF added.