“She beat me before,” Serena Williams informed her BBC interviewer after semifinal victory at Wimbledon on Thursday, when asked about the woman she would meet in the final, Garbine Muguruza.

Serena said it as if she expected the news to surprise him a little. And maybe it did. Muguruza is a 21-year-old from Spain, ranked 20th in the world; this is the first time she has reached a semifinal at a major, let alone a final. Would you expect her to have a win over Serena already? The only thing more surprising than the result were the scores: In the second round at last year’s French Open, Muguruza bowled Serena over and knocked her out of the tournament, 6-2, 6-2.

“She made me improve,” Serena said. And maybe that’s true. Williams had been No. 1 for two years before that match, but if anything she’s been even better in the 13 months since. During that time, Serena has won three Slams, and has lost just one match anywhere in 2015.

One of her wins this year came against Muguruza at the Australian Open, but it wasn’t easy. The Spaniard won the first set, again by a 6-2 score, by doing what she had done to her in Paris: Jumping on the ball ASAP and driving it straight down the middle of the court—leaving Serena, who loves to create angles from the baseline, with none to create. In Melbourne, though, Serena found a way out of the box that Muguruza had put her in, and found a way to start dictating play. Serena won the last two sets 6-3, 6-2. Much like in her Wimbledon semifinal against Agnieszka Radwanska on Thursday, Muguruza couldn’t redline her game for two straight sets.

Can she do it against Serena this time? Muguruza has shown no fear yet, of the moment, the stage, or her opponent. She knows that if she’s serving well and making her shots, she can stay with anyone. Grass will be the fastest surface they’ve played on, but I don’t think it favors either woman—they’re power players wherever they go. A bigger factor could be nerves; which woman will handle them better when the finish line approaches? Both Serena and Muguruza have surrendered one-set leads at this event, and it won’t be surprising if one of them does it again on the biggest stage of all.

Muguruza has a chance. If she can get into a groove, and somehow keep herself from thinking about what’s happening, she has the game to win. But judging by the way Serena roared back to beat Victoria Azarenka in the quarters, and maintained her edge and nerve so meticulously against Maria Sharapova in the semis, I don’t think she’s come this far—at Wimbledon, in her quest for another Serena Slam, or in her quest for a calendar-year Grand Slam—to lose now.

Winner: Serena Williams