Since beginning her career in 1995, Serena Williams has been one of the few constants in women's tennis. Champions have come and gone in the span of her career; rivals have been eliminated; even her sister, Venus, has seen an unfortunate and precipitous decline in her abilities due to her battles with Sjögren's syndrome and back injuries. Serena, however, has kept on chugging. Nothing has stopped the Compton, Calif. native on her path to becoming not only the greatest women's tennis player of her era, but of all time, and, arguably, the greatest tennis player ever, period. 

Currently, Williams has 20 Slams to her name, with no. 21 on the line Saturday versus the 21-year-old Garbine Muguruza. Should she win yet another Wimbledon title, she'll be just one Slam behind Steffi Graf for most titles in the Open era, and three away from tying Margaret Court for the most all-time. Yes, history is on the line. 

Of course, that's not the title's only significance. Currently, Serena is the titleholder for the U.S. Open, French Open, Australian Open, meaning that if she wins Wimbledon, then she'll have completed the second non-calendar Grand Slam of her career, joining the ranks of, well, herself as the only women's singles player to have accomplished the feat twice. 

The last time Serena pulled off a "Serena Slam," she won every title from the French Open in 2002 to the Australian Open in 2003. This time around, it starts with the 2014 Australian Open, and ends tomorrow at Wimbledon. As you'll see from the list we've assembled below, a lot has changed since that first run of brilliance. Take a look for yourself to see what the world looked like when Serena last completed a "Serena Slam," on January 25, 2003