MIAMI, Fla.—For a while there today, it looked as if that bump on the head Li Na suffered in the Australian Open final—and the long, subsequent layoff—might have caused her to forget how to play tennis. For after jumping out to a 5-1 lead over 19-year-old Garbine Muguruza, Li’s mind wandered and almost left the island of Key Biscayne.

Li remembered the task at hand in the nick of time, although she had to fight her way into a tiebreaker—one in which she would waste a 6-1 advantage. At that point, the set suddenly seemed to be beyond her grasp, like a misplaced set of car keys. But after rifling through her mental bag, frantically probing the seat cushions, and repeatedly patting her pockets, she finally secured the tiebreaker, 8-6. She went on to win the match, 7-6 (6), 6-2.

“I was feeling pretty good at start (of the match),” Li would tell me later. “So, okay, I should continue. But maybe I think too much out of the tennis. Tennis is more important to think point-by-point, what you should do on the court.”

Li confessed that after building that towering lead, she began to think about “the wind”—of which there was little today, but when do such details ever matter when a player has taken a mental vacation? She also thought about “the people”—not their plight, or needs, the way the new Pope might. It was more like, “What’s with that funny hat?” or “Put the cell phone away, bubble-brain.” In other words, Li engaged in some garden variety spacing-out, and it almost cost her the set.

“At six-five in the tiebreaker, I was saying, ‘Don’t do the same thing again!” (A reference to letting that earlier, 5-1 lead in games slip away.)

Not long before that, when Muguruza won her fourth consecutive game to take a 6-5 lead in the set, Li looked at her guest box and shrugged helplessly. She hadn’t signed up for on-court coaching, so she had to settle for a simple hand gesture from her coach, Carlos Rodriguez. He made the universal, palms down signal—suggesting that she calm down—a signal that Li has come to recognize easily. Rodriguez has been trying to get the restrained and reticent but tightly wound Li to relax a little more frequently since the day he signed up for the job about six months ago. Let’s just say that goal is a work in progress.

“After I see him, I was thinking, okay, six-all and in the tiebreaker. Everyone has a chance. Even if I lose first set, I still have a set to go. Don’t think about the score. Just do our job on the court.”

Li remembered enough of her job description to survive, and now she’s into the quarterfinals of the first tournament she’s played since that memorable night when everything seemed to go wrong for her at the most inconvenient time—in the Australian Open final. She took a bad tumble in that match (a three-set loss to Victoria Azarenka), resulting in a damaged ankle and a mild concussion when she banged her head on the hard court.

After resting in China for a week, Li took off for Germany, where her head checked out fine, but she was diagnosed with plantar fasciitis-like ligament and bone problems. She sojourned in Germany for three weeks, unable to much besides gym work, then returned to Beijing, where she and Rodriguez adopted a day-to-day approach to her on-court training.

They also worked on an aspect of their relationship that Li has come to prize, now that she and Rodriguez are beyond the honeymoon phase of their relationship: Communication. Li was surprised by how much Rodriguez liked to talk and communicate, and even more amazed at how easily his proclivities that way rubbed off on her. “I am really happy I can work with him,” she said. “He never gives me the pressure, he always tries to learn me to speak out.”

Li went on to surmise that Chinese, in general, are a little different than westerners in how easily or freely they express themselves. Speaking for herself, Li admitted that she had always tended to clam up, to keep her thoughts and feelings bottled up. “I always before like to hold (those feelings and thoughts) to myself,” she confessed. “Before, my team didn’t even know what I was thinking about before a match. Now, if feeling uncomfortable, happy, whatever . . . I feel I can speak out and the team can share how I am feeling.”

On court, though, Li remains a model of reserve—in fact, it’s one of her most appealing qualities. It’s an understatement to say that she had unlimited opportunities today to blow her cork, or even just to match her precocious opponent with a triumphant if not particularly menacing fist pump now and then. Even at the worst of times, though, Li kept her own counsel. There’s a quiet but shining dignity about this woman, even when her manner makes her look lonely out there.

Incidentally, Muguruza is developing nicely and adding yet another stylish element to the growing, diverse list of talented Spanish players. A six-footer, Muguruza hits a clean, relatively flat, hard ball. She sometimes looks and plays like an elongated version of Jennifer Capriati, although she has yet to show anything like the American’s facility for winning the big points and keeping her foot pressed to the accelerator. Li won their only previous meeting, on clay last year in Madrid. She too noticed the difference in Muguruza’s game.

“Last year, if I hit a little heavy to her forehand, she always made mistake,” Li said. “But this time some points she plays unbelievable. She plays good defense, close to the baseline. Between the balls it goes a little bit fast. I was a little bit (rushed). Sometimes I didn’t have time to do things. If I play her again I will never do the same way.”

Good idea. I suppose we’ll see how well Li’s memory holds up.