But the want-to factor, the sheer will to impose herself, is what separates Williams from all the other women who make a living playing tennis. For three sets in a row -- the first two coming against Maria Sharapova in the semifinals -- Williams wandered into those frames, seemingly disinterested. Only when she found herself in a formidable hole did she find some fire.
Li, playing spectacularly, crafted a 5-2 lead in the opening set of their Sony Open Tennis final Saturday. But Serena dialed in and won the last five games and, ultimately, 11 of the final 12. Li's resolve and, not coincidentally her heavy groundstrokes, broke down.
After that, the 7-5, 6-1 result was painfully predictable. Serena collected her unprecedented seventh Miami title -- she feels most comfortable at her hometown tournament -- a crystal vase trophy and, not insignificantly, $787,000.
Serena is so good that opponents can lose badly and still feel good about their games. Li won a single game in more than an hour's time on the backside of the match, yet seemed upbeat afterward when someone asked what went wrong.
"Is not wrong," she said, frowning. "I don't think I was playing bad. Maybe she just start a little bit better after 5-2 down.
"I mean, really nothing to say. I think it was a pretty good match. I don't think today I was doing like a wrong game plan or I was playing totally wrong. Yeah, that's what I think."
Serena, who is a part owner of the Miami Dolphins, along with her sister Venus, wore the team colors of orange and aqua blue.
"Oh, I definitely don't do it on purpose," Williams said. "I don't know. Maybe I get a little nervous because I want to do so well, and I want to -- I just want to win, and then sometimes if you get too nervous you're not able to play."
Tennis may be a game for the young, but Williams and Li are the No. 1- and No. 2-ranked players at the age of 32. Li is the reigning Australian Open champion and has the second-best record, 21-3, although this was, surprisingly, her first match against a top-10 player. Williams, of course, is the best, at a sporty 15-2.
Here is how utterly dominant Serena has been against the best women's tennis has to offer:
• The No. 2-ranked Li is now 1-11 against Williams.
• No. 3 Agnieszka Radwanska is 0-8.
• No. 4 Victoria Azarenka is 3-14.
• No. 7 Sharapova is 2-16.
It all adds up to a combined record of 49-6 -- a winning percentage of 89 percent. Savor those numbers because there is currently no parallel in any other major individual sport, no greater disparity between one player and the rest of his or her elite peers. Michael Phelps, the swimmer, might come close. But Roger Federer and Tiger Woods, even in their salad days, were never that dominant.
At her (relatively) advanced age, Williams is still bringing it. She determines the outcome more than any opponent. If she's feeling it, is truly motivated to beat a great player, she almost always does it.
She's lost only twice this year, and it's instructive that those defeats came at the hands of Ana Ivanovic (Australian Open) and Alize Cornet (Dubai). In the past nine majors, Williams has won four titles, and her three losses before the quarterfinals were to Sloane Stephens, Virginie Razzano and Sabine Lisicki.
But when she steps on the court for a final, Williams smells blood. Or, at the very least, profound doubt.
Since falling to Samantha Stosur in the 2011 US Open final, Williams has won 20 of 22 finals, losing to Azarenka twice last year.
Serena, who lives a modest drive from the Crandon Park facility, has been commuting from the Key Biscayne Ritz Hotel this week. Her Miami record is a smoking 67-7 and her titles span 13 years. Her first appearance here came at the age of 16, so the event encompasses half her life.
Coming in, Li actually had a chance to make inroads on Serena's No. 1 ranking. Williams was the defending champion here and also at the French Open. Li won Williams' first service game and took care of her own, saving three break points at 2-1. When Williams double-faulted to give Li a 5-2 lead, it looked as though Li was a lock for the first set. But Serena broke her in back-to-back service games; the 10th game with Li serving again for the set at 5-4, had some terrific stuff. In the end, Serena was made of sterner stuff.
Hard to believe, but Williams put fewer than half of her first serves in play.
"I think that's what I've mostly been able to develop mostly in my game in the past," Williams said. "If my serve isn't going great, my whole game kind of went down. And I think now if my serve isn't great, it's OK because I have a great forehand, I have a great backhand, I have great speed. If push comes to shove, I will come to the net."
Li and Williams were laughing together at the presentation ceremony, about how two elderly women could be playing so well. Li, who calls herself a "young" 32, actually sounded older than her age when she talked about Miami's Ultra music festival that began last night. The noise, from acts like Bro Safari, Umek and BlasterJaxx, she said, made it difficult to sleep in her downtown hotel.
"So many young kids with strange dress," Li said. "Always can see the young kids like going crazy like drunk, totally. I was like, 'Wow, we really are old.' Maybe this is the fashion, but we cannot take it."
At the end, though, Serena jumped up and down like a 6-year-old.
"I was actually super excited at the end," Serena said, "because I remember sitting here last year trying to get to six, thinking, 'OK, obviously I want seven, but I don't want to put the pressure on myself to get to seven.' Obviously I wanted to have the most titles here.
"I guess that I've grown up coming to this tournament as a kid, watching so many players, and to be one of those players now is really, really awesome for me."