Before the two face off on Philippe Chatrier, here are 10 points to ponder...
1) Serena is a win away from some major milestones.
Not only is Serena one win away from equaling Steffi Graf's Open-Era record of 22 Grand Slam titles (Margaret Court holds the all-time lead with 24) but she's also trying to become just the fourth player in the Open Era to win four or more titles in Paris (after Chris Evert (seven), Graf (six) and Justine Henin (four)).
2) Age is just a number.
Aged 34 years, 252 days, Williams is looking to become the oldest Roland Garros champion of all-time. The current holder of this particular record is 1958 winner, Zsuzsi Kormoczy, who was 33 years, 279 days.
3) Big time rivalry.
As with most of her rivals, Williams holds the edge in previous meetings with Muguruza. All four of these have come at Grand Slams, Williams triumphing at the Australian Open in 2013 and 2015, and also in the 2015 Wimbledon final. However, Muguruza's sole victory did come on clay. And in emphatic fashion - the then 20-year-old upsetting Williams, 6-2, 6-2, in the second round of Roland Garros in 2014.
4) The final challenge.
Defeating Williams in a final is a different proposition entirely. The American has only lost two of her 15 clay court finals (both to Henin, at 2002 Berlin and 2003 Charleston). Her record in major finals is equally impressive, winning 21 of 26 (.808), her only losses coming at the hands of Venus Williams (2001 US Open, 2008 Wimbledon), Maria Sharapova (2004 Wimbledon), Samantha Stosur (2011 US Open) and Angelique Kerber (2016 Australian Open). In fact only Margaret Court, who won 24 of 29 (.828), has a better record.
5) The wait is over.
Muguruza's win over Samantha Stosur ended a 16-year wait for a Spanish finalist at Roland Garros. The last player hailing from the Iberian Peninsula to do so was Conchita Martínez, who lost to Mary Pierce in the 2000 final. Muguruza, who remarkably will be contesting her very first final on clay, will bid to become the first Spaniard to win the title since Arantxa Sánchez-Vicario in 1998.
6) Forget the history books, Garbiñe.
Muguruza will do well to forget what happened to the last player to contest their career-first clay court final at Roland Garros; in 1988 a 17-year-old Natasha Zvereva lost 6-0, 6-0 to Graf in just 34 minutes - the shortest final in the tournament's 125-year history.
7) Both players will soar up the Road To Singapore.
After a slow start to the season Muguruza arrived in Paris at No.17 on the Road To Singapore leaderboard. Her accomplishments this past fortnight guarantee that she will leave at No.5 (or No.4 should she win the final), while Williams will rise from No.3 to No.1.
8) Defending title in Paris a rare feat.
Defending her title in Paris is one of the few accomplishments to have eluded Williams. She is in good company, though. Only five players in the Open Era have successfully defended the French Open: Margaret Court, Chris Evert, Steffi Graf, Monica Seles and most recently Justine Henin (in 2007).
9) Contrasting paths to the final.
Since dropping the opening set of her opening match, against Anna Karolina Schmiedlova, Muguruza has been virtually flawless. She has won 12 sets in a row since her first-round wobble, spending eight hours and 33 minutes on court. Williams took just 14 minutes more to reach the final, also dropping one set, but had a few hairy moments, none more so than her quarterfinal with Yulia Putintseva, when she came within five points of defeat.
10) Muguruza no stranger to the big occasion.
While her experience pales in comparison to the woman standing on the other side of the net, Muguruza is stranger to performing on the big occasion. Last summer, she acquitted herself well in a competitive Wimbledon final against Williams, she has five wins against fellow members of the Top 5 and also won the Premier Mandatory China Open last October.