It was a heated rivalry between Serena and Maria over the years with Williams being the more successful player both overall and in the H2H. At times it became so heated that many fans thought they hated each other and while not far from the truth, there was a certain dose of respect there from the start.
In a recent interview, Williams revealed something that surprised many of their fans claiming that they are best friends now. It's not that surprising as their relationship softened up over the years but 'best friends' isn't something that Serena would use lightly.
She also apologised to Caroline Wozniacki who held that title before as Williams admitted that Maria and her bonded over parenthood:
“She is my best friend now. Sorry, Caroline. Also the first person I can call to discuss my day-to-day things with. Motherhood has brought us really close to each other”
They also share a keen interest in business investing in several platforms so perhaps they share talks on that topic as well.