Serena Williams responds to bombshell news of close friend Meghan Markle and Prince Harry's royal resignation

Meghan Markle sat in the team box with Serena Williams' mother, Oracene Price (left), at last year's US Open. Photo / Getty Images

Tennis superstar Serena Williams has refused to be drawn on the news that her close friend Meghan Markle and Prince Harry were quitting as "senior royals".

The couple's announcement on Thursday sent shockwaves through the royal family and forced Buckingham Palace to respond with a rare public statement, implying an unprecedented split in the monarch.

"Discussions with the Duke and Duchess of Sussex are at an early stage. We understand their desire to take a different approach, but these are complicated issues that will take time to work through," the statement read.

Williams, who is playing at the ASB tennis Classic in Auckland, was asked for her thoughts on the news involving her close friend, the Duchess of Sussex.

"Oh, I am not touching that - so thank you," Williams said before giving a nervous giggle.

Meghan Markle and Serena Williams participated in the DirecTV Beach Bowl in 2014. Photo / Getty Images

In November last year, the 23-time Grand Slam champion opened up on her tight bond with Meghan in an interview with Access Hollywood, saying the former Suits star was "literally the strongest —person I know, and the nicest, sweetest".

Williams and Markle have been good friends since meeting at a Super Bowl party in 2010, with the Duchess flying to last year's US Open to support Williams.

"She flew all the way with a newborn to see me play in New York and flew all the way back that night, and I probably couldn't have done that," Williams told Access Hollywood.

"It just kind of goes to show you what an amazing person that she is, and that's just one of the many things that she does for me.

"I call her, text her anytime, crying, upset—she's always there. Doesn't matter what she's going through, she just sets time away, and she's just so amazing."

Williams also attended the royal wedding Markle's wedding at St George's Chapel, Windsor Castle, on May 19, 2018.

Williams, who will be attempting to equal Margaret Court's record of 24 Grand Slams at the Australian Open later this month, was made to work hard in her second-round clash with Christina Mchale, eventually beating her fellow American in three sets.