Winning streaks, finals streaks, Grand Slams performances and her magnificent record since joining forces with Patrick Mouratoglou - a bevy of the best Serena Williams stats are right here...
WTA Staff

PARIS, France - Serena Williams has resumed her relentless march towards tennis history at Roland Garros this fortnight. As she closes in on a 22nd Grand Slam crown, here are some noteworthy numbers on the WTA's indomitable World No.1.

(updated after her semifinal win at the French Open)

Serena & Grand Slams
~ Serena has the second-most Grand Slam singles titles in the Open Era with 21 (Graf 22)
~ Serena has the third-most Grand Slam singles titles all-time with 21 (Court 24, Graf 22)
~ Serena has the third-most Grand Slam match wins in Open Era with 297 (Navratilova 306, Evert 299)
~ Serena is trying to win her fourth Roland Garros title (won it in 2002, 2013 and 2015); a fourth title would tie her with Justine Henin and Helen Wills-Moody on the all-time leaderboard
~ This is Serena's 21st time being the No.1 seed at a Grand Slam (she's won 11 of the first 20)
~ Serena is 21-5 in Grand Slam final matches (her five defeats came against Venus Williams (2001 US Open, 2008 Wimbledon), Maria Sharapova (2004 Wimbledon), Samantha Stosur (2011 US Open) and Angelique Kerber (2016 Australian Open))

Serena & Finals
~ Serena is 21-5 in Grand Slam singles finals, the second-best winning percentage Open Era (Court was 11-1)
~ Serena won eight straight Grand Slam singles finals between 2012 Wimbledon and 2015 Wimbledon; losses on each side were 2011 US Open (l. Stosur) and 2016 Australian Open (l. Kerber)
~ Serena has won 31 of her last 35 finals (only losses: Azarenka at 2013 Doha, 2013 Cincinnati, 2016 Indian Wells & Kerber at 2016 Australian Open)

Serena & Age-Related Stats
~ Serena is the oldest woman to win a major in the Open Era (33y & 285d at 2015 Wimbledon)
~ Serena is the oldest No.1 in WTA history (set record when returned to No.1 on February 18, 2013)
~ Serena has the longest winning span between majors of any woman Open Era at 15 years and 10 months between 1999 US Open and 2015 Wimbledon (Evert, Navratilova and Graf had 12-year spans)
~ Serena has won eight majors since turning 30, the most after 30 by far in the Open Era (Court and Navratilova three each, King and Evert two each and Jones, Wade, Li and Pennetta one each)

Miscellaneous
~ Serena will spend her 171st & 172nd straight weeks at No.1 during the Roland Garros fortnight (second-longest streak at No.1 in WTA history after Graf's 186)
~ Serena is spending her 294th & 295th career weeks at No.1 during the Roland Garros fortnight (second-most weeks at No.1 in WTA history after Graf's 377)
~ Serena has the most career prize money in WTA history ($76.5M - next-most is Sharapova's $36.8M) 
~ Serena has the fifth-most WTA titles in Open Era with 70 (after Navratilova, Evert, Graf, Court)

Before & After Patrick Mouratoglou
Serena joined forces with Patrick Mouratoglou after falling first round at the 2012 French Open, and the dynamic duo's numbers speak for themselves - here's a comparison of before and after Mouratoglou:

Pre-Patrick Mouratoglou
win-loss: 523-107 (.830)
WTA titles: 41
Grand Slam titles: 13 out of 47 (.277)
vs Top 10: 111-59 (.653)

Post-Patrick Mouratoglou
win-loss: 238-19 (.926)
WTA titles: 29
Grand Slam titles: 8 out of 15 (.533)
vs Top 10: 56-6 (.903)

Since Regaining World No.1
Since returning to the top spot on the WTA Rankings on February 18, 2013, Serena's been fantastic:
win-loss: 195-16
WTA titles: 23 of 33
Grand Slam titles: 6 of 12
vs Top 10: 41-4 (.911)