"I want to invest in B-to-B [business-to-business] companies and know how I could invest in early stage companies early on and have a big reward.
Williams also owns production company Nine Two Six and wrote a children's book called The Adventures of Qai Qai.
The unicorn companies that have received investment from Serena Ventures include Impossible Foods, the plant-based food production company, and Masterclass, which is valued at $2.75bn.
But she always had one eye on the future and launched venture capital fund Serena Ventures in 2017 - five years before she hung up her racket for good.
Most of her success has come with Serena Ventures, which has invested in 85 companies - 14 of which have been 'unicorn' companies.
