Serena Williams' fiance says she'll be an 'awesome' mom

— -- Serena Williams' fiance, Alexis Ohanian, is confident she will be a great mother.

"She's very good at a lot of things and well on her way to being an awesome mom too," Reddit co-founder Ohanian, 34, told CNBC's "Squawk Box" in a recent interview.

Ohanian and Williams, 35, the winner of 23 Grand Slam singles titles, got engaged in December. In April she revealed on Snapchat that they are expecting their first child.

The baby is due this fall, and Ohanian told CNBC he plans to take time off.

"At Reddit it's really important for us to support men and women when they are welcoming a new member to the family, and so we have a pretty generous parental leave policy. I'll be taking off for six weeks myself and trying to do the best job possible as a new dad, a first-time dad," he said. "We want to break that stereotype that the men work and the women take care of kids. We want to give that opportunity to everyone."

Williams, who recently posed nude on the cover of Vanity Fair, said she plans to return to the tennis court after giving birth.

"I don't think my story is over yet," she told the magazine.