Swiatek, who lifted the Suzanne Lenglen Cup last year and in 2020, was put through the wringer by Haddad Maia but held her nerve in a tense tiebreak to see off the 14th seed's challenge.
"She has a really nice game for clay courts with a lot of top spin," Swiatek said of Haddad Maia, who beat the Pole in their only other meeting in Toronto last year.
There was light at the end of the tunnel for Japan's Miyu Kato after a difficult few days, as she put her women's doubles disqualification behind her to claim the mixed doubles crown with Germany's Tim Puetz.
Kato and her Indonesian partner Aldila Sutjiadi had been disqualified from the women's doubles in the third round when Kato hit a ball down the court between points, inadvertently striking a ball girl.
I'm doing my best so we can one day return and claim the women's doubles title."
Persons:
Haddad Maia, Sabalenka Kato, Iga Swiatek, Beatriz Haddad Maia, Roland Garros, Karolina Muchova, Suzanne Lenglen, Swiatek, Muchova, Jelena Ostapenko, Miyu Kato, Tim Puetz, Canada's Bianca Andreescu, New Zealander Michael Venus, Kato, Aldila Sutjiadi, I'm, Carlos Alcaraz, Novak Djokovic, Casper Ruud, Alexander Zverev, Karolos Grohmann, Julien Pretot, Shrivathsa Sridhar, Ed Osmond, Pritha
Organizations:
PARIS, New Zealander, Thomson
Locations:
Toronto, Paris, New