Now she finally has it. And so she can flaunt it.
Williams lifted both arms overhead and raised two fingers on each hand right there on Centre Court to show off the magic number after winning her record-tying 22nd Grand Slam singles title by beating Angelique Kerber 7-5, 6-3 in the Wimbledon final Saturday.
"Yeah, it's been incredibly difficult not to think about it. I had a couple of tries this year," Williams said during the trophy ceremony. "But it makes the victory even sweeter to know how hard I worked for it.
"I have, yeah, definitely had some sleepless nights, if I'm just honest, with a lot of stuff. Coming so close. Feeling it, not quite able to get there."
She pulled even with Steffi Graf for the most major championships in the Open era, which began in 1968. Now Williams stands behind only Margaret Court's all-time mark of 24.
This was Williams' seventh singles trophy at the All England Club -- only Martina Navratilova, with nine, has more -- and her second in a row. Her victory at Wimbledon a year ago raised her Grand Slam count to 21, but while she almost had added to that total since, she was not able to.
There was a stunning loss to Roberta Vinci in the US Open semifinals in September, ending Williams' bid for a calendar-year Grand Slam. Then came losses in finals to Kerber at the Australian Open in January and to Garbine Muguruza at the French Open last month.
"If I'm totally honest, I'm not relieved to have the 22nd, I'm relieved to have Serena back," said Williams' coach, Patrick Mouratoglou. "Everything depends on that. I don't look at the reward, I look at how to achieve it. And there was something missing for a few months, and the thing that was missing was just Serena. The tennis player was there, but Serena as a person wasn't really herself so she was much more beatable.
"She got that back over time. I think we didn't realize how much time she need to recover from the loss at the US Open. Maybe I'm being wrong, but that's how I feel."
And if having the singles title wasn't enough, she later teamed up with sister Venus Williams on Centre Court to capture the women's doubles championship -- their sixth at Wimbledon -- with a 6-3, 6-4 victory against Timea Babos and Yaroslava Shvedova.
In the rematch against the fourth-seeded Kerber on Saturday -- the first time in a decade two women met to decide multiple major titles in a single season -- the No. 1-ranked Williams came through. This goes alongside her six championships at the US Open, six at the Australian Open and three at the French Open.
The 34-year-old American did it, as she often does, with nearly impeccable serving. She slammed 13 aces, including at least one in each of her first eight service games. She won 38 of 43 points when she put a first serve in.
She faced just one break point -- at 3-all in the second set, it represented Kerber's only real opening -- and shut the door quickly and emphatically, with a pair of aces at 117 mph and 124 mph, her fastest of the afternoon.
"This court," Williams said, "definitely feels like home."
There was more that Williams did well, though. So much more. Facing the left-handed Kerber's reactive, counterpunching style, Williams was by far the more aggressive player during baseline exchanges, trying to make things happen. And she did, compiling a big edge in winners, 39-12.
Williams returned well, hammering second serves that floated in at 75 mph and breaking serve once in each set. She volleyed well, too, winning the point on 16 of 22 trips to the net, including a tap-in on the last point. Soon enough, she was wrapping Kerber in a warm embrace, then holding up those fingers to symbolize "22."
"At the end, I was trying everything, but she deserved it today. She really played an unbelievable match," said Kerber, who hadn't appeared in a major final until beating Williams in Melbourne. "I think we both played on a really high level."
It was breezy, but that didn't seem to hamper Williams, whose older sister Venus sat in her guest box, a couple of seats over from music's power couple of Beyoncé and Jay Z.
Kerber, a German who knows Graf well, defeated Venus in the semifinals and hadn't dropped a set on her way to the final. But on the grass that suits Williams' game so well, Kerber simply could not quite keep up with the trophy on the line, although it was a high-quality match that was more competitive than the scoreline might indicate.
"I also played a good match," Kerber said. "That makes it a little easier for me."
Williams lost only one set this fortnight, the opener of her second-round match against AmericanChristina McHalelast week. After dropping that tiebreaker, Williams sat in her sideline chair and proceeded to smack her racket repeatedly against the grass, before flinging the equipment so far behind her that it landed in the lap of a TV cameraman.
That earned Williams a $10,000 fine, but perhaps it pointed her in the right direction. She won all 12 sets she has played since.
"Once I started focusing more on the positives, I realized that I'm pretty good," she said. "Then I started playing a little better."
Said Mouratoglou: "What you saw today, what you saw in the semis and what you saw in the second-round round [against McHale], that was Serena. When she was in trouble -- boom, boom, she did it. When she needed to close -- boom, she did it. That is Serena. I didn't see that for months."
There had been some thought that Williams was really stung by her loss to Vinci in New York, that it was too big a disappointment to push aside and lingered, somehow, when she followed with the setbacks against Kerber and Muguruza.
"If anything, I was able to show resilience that, no, that's not going to shake me, you're not going to break me," Williams said, "it's going to make me stronger."
So, Williams was asked Saturday, is she already thinking about No. 25, to surpass Court?
"Oh, God, no," Williams said. "One thing I learned about last year is to enjoy the moment. I'm definitely going to enjoy this."
The Associated Press contributed to this report.