Serena Williams holds the U.S. Open tennis women's singles championship...

Serena Williams holds the U.S. Open tennis women's singles championship trophy during a visit to the 103rd floor of the Empire State Building, Monday, Sept. 8, 2014, in New York. Williams defeated Caroline Wozniacki, 6-3, 6-3 on Sunday to win her third straight U.S. Open. Credit: AP

Serena Williams is building a new house, complete with a karaoke room and a purse room for her "bag problem."

She and big sister Venus are finally moving apart after more than three decades -- though they'll still live down the street from each other in Florida. Serena joked Monday that she was contemplating scaling down the plans until she won a record $4 million prize at the U.S. Open.

She's going for a "South of France meets Northern Italy" look, and there will be a trophy room, too. Williams won her 18th piece of Grand Slam singles hardware Sunday, matching Chris Evert and Martina Navratilova.

The Open-era record is 22 titles by Steffi Graf.

"If anybody can do it, it's her," Navratilova said Sunday after she and Evert presented Williams with an 18-karat gold bracelet. "It gets tougher after 30, but Serena is relatively young in tennis matches."

Williams, who turns 33 in 2 1/2 weeks, has played 795 career singles matches. For comparison, Roger Federer -- who turned 33 last month and is now one behind her with 17 major titles -- has played 1,202.

"I think she's eager and she's strong," Navratilova added, "and there's nobody nipping at her heels."

On Monday, Williams would say only that her next objective is 19, but if "I get to 19, knowing me, 20 will be my goal."

And so on and so on? Williams acknowledged she'd love to go out on top, but it's more of a dream scenario than a plan to retire immediately after a championship.

Graf still inspires awe in her.

"She was just so cool," Williams said. "I loved how fast she played and how fast she walked. She just seemed so serious -- all about business."

Williams takes that approach even in practice, saying she never smiles and sits in a corner with her back turned during breaks.

Yet once the tennis ended Sunday, a very unusual scene for a major sports event unfolded: Williams and the player she defeated in the final, Caroline Wozniacki, went out celebrating together that night.

"She stole my phone," a laughing Williams said of her good friend.

Wozniacki was posting photos to Instagram with singer Joe Jonas and model Gigi Hadid. On Tuesday, she plans to attend Williams' first Fashion Week show.

Williams, who was pleased she stayed so relaxed throughout the U.S. Open, is feeling the pressure of this new venture.

"Someone invited me to go hang out on their boat, and I'm like, 'No, no, I'm going to be real stressed out tomorrow,"' she said. "I have to make sure the girls look good, the models are right. I need to make sure they have the walk right."

The sense of calm during her waking hours the past two weeks did not extend to her dreams. Williams said she had more nightmares than usual.

Losing to Victoria Azarenka in a quarterfinal. Falling down and missing a match.

"It felt so real," she said. "I wake up so stressed."

But when she took the court for Sunday's final, the vibe was positive. CBS had just broadcast a victory by the Miami Dolphins, in which she owns a small stake, over the New England Patriots, and now the network was going to air her match.

Williams doesn't want to talk about her place in history until her career ends. But she'll allow herself brief moments to reflect back.

When she practices in Arthur Ashe Stadium, she remembers where on the court she celebrated championships -- she realized she's clinched more titles to the left of the umpire's chair.

And occasionally she'll pull up an old match on YouTube. Recently she stumbled across a 1999 meeting with Monica Seles and was stunned to see that teenage version of herself.

"I went to the net. What happened to that girl?" she said. "She was awesome. I didn't complain. I was so positive. I lost points and you would've thought I won."

These days it's obvious whether she won or lost a point by her reaction. But Williams was able to stay positive on the court during the U.S. Open, and the results were dominant. As far as her fitness, she joked that "30 is definitely the new 15."

"Every year I feel better," Williams said. "It's the weirdest, strangest thing."

Maybe 22 Grand Slam titles don't sound so odd after all.

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