Serena Williams Wimbledon 2015
American Serena Williams enters the 25th grand slam final of her career against Garbine Muguruza in the women's Wimbledon final Saturday at All England Club. Getty Images

Throughout her incomparable career, Serena Williams has felt the atmosphere and pressure of a grand slam final 24 times and has proven victorious in 20. The American’s foe in Saturday’s Wimbledon final, 21-year-old Garbine Muguruza, steps onto the total opposite side of the experience spectrum in the first slam final of her career.

No. 1 Williams stands as the heavy favorite to claim the 21st title of her career, but Muguruza’s refusing to back down from the challenge.

“To have Serena in the Wimbledon final, I think, is the hardest match you can have,” Muguruza said to the New York Times. “If you want to win a Grand Slam, when you dream, you say, ‘I want Serena in the final.’ ”

And Williams she will have, one that’s healthy, lost only two sets in her six wins to reach the final, and holds a near immaculate 32-1 singles record this year. Williams has already claimed the French and Australian Opens, and is on the cusp of winning the year’s first three slams for the first time in her career.

The 33-year-old also blasted her closest rival, No. 4 Maria Sharapova, 6-2 6-4 in the semifinals, but Williams isn’t looking past No. 20 Muguruza despite all her experience.

"We had a tough match the last time we played. And she's given me problems in the past," Williams said of Muguruza after the semis. "So this time I have to just go in it ... and do the best that I can, just try to stay positive and stay focused."

Though they’ve met only three times, the last time Muguruza got the better of Williams in the second round of the French last year, a punishing 6-2 6-2 upset. And Williams hasn’t enjoyed recent success on Wimbledon’s grass like the hard courts in Australia or the U.S. She won Wimbledon in 2012, the last time she reached the final, and succumbed to fourth- and third-round exits since then.

But one more victory will put Williams only one slam behind Steffi Graf’s 22, and she’s looked stronger, even overpowering, prior to the final. Williams has fired off 60 aces in the tournament, 13 of which came against Sharapova, one of the top returners in the world.

Muguruza’s welcoming the challenge and thus far she’s outplayed higher-ranked and more experienced players to elevate her confidence. She fought off a grueling 14-12 first set tiebreaker to oust No. 10 Angelique Kerber in the third round, and followed up with sweeps of No. 5 Carolina Wozniacki and No. 15 Timea Bacsinszky before outlasting No. 13 Agnieska Radwanska in the semis.

"She knows that I can win against her, that I'm not afraid," Muguruza added. "I don't think she's really used to this. Serena, she doesn't lose so many matches in the year."

Start Time: 9 a.m. ET

TV Channel: ESPN, BBC1

Live Online: Watch ESPN

Prediction: With her big serve and fleet footwork, Williams stands well above Muguruza before the match and will likely do so after it. Muguruza has the younger and fresher legs, and plays well at the net, but a repeat of her 23 unforced errors in the semis will get her in serious trouble against Williams. It’s possible Muguruza takes the second set, but Williams should prevail in two straight.