Serena Williams breaks her silence on Ilie Nastase's racially charged comment about her baby

Serena Williams posted a powerful response to Instagram after Romania's Fed Cup captain Ilie Nastase was overheard making a racially charged remark about her unborn child.

"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," the 35-year-old wrote.

"I have said it once and I'll say it again, this world has come so far but yet we have so much further to go," the top-ranked athlete added in her response. "Yes, we have broken down so many barriers - however, there are a plethora more to go.

The International Tennis Federation announced on Monday that they were investigating the alleged derogatory comments. The 70-year-old was overheard talking to a team member about Williams' recent pregnancy announcement, saying "Let's see what color it has. Chocolate with milk?"

"The ITF does not tolerate discriminatory and offensive language and behavior of any kind," the ITF said in a statement responding to the alleged comments.

Williams announced the pregnancy with her fiancé on Snapchat last week. The tennis star got engaged to Reddit co-founder Alexis Ohanian, who is white, in December 2016. The pair has been dating since 2015.

Their baby is due to be born this fall.

Venus and Serena Williams through the years

The 23-time Grand Slam champion reclaimed the No. 1 ranking on the Women's Tennis Tour on Monday morning. She most recently defeated her sister, Venus Williams, in the Australian Open final in late January.