With temperatures steadily soaring on the sixth day of the Grand Slam, Swiatek appeared in a hurry to escape the Parisian furnace and the five-time major winner raced through the first set on the back of two breaks.
What followed was a high-quality battle where both players tested each other before Swiatek prevailed after keeping cool in the final game of the second set.
"I'm just happy that I was super solid in that last game and did not give her any free points," said Swiatek.
"She went for it, and it was a great match. We both played nice and I'm happy with my performance."
Swiatek cooled herself with ice towels after the first set before coming under pressure from unseeded Romanian Cristian on Court Suzanne Lenglen in the second set, but the 23-year-old produced a tight hold in the third game.
Both players went toe-to-toe from there, and Cristian hit a stinging forehand winner to level up at 4-4, raising her level again to hold serve two games later and prolonging Swiatek's stay on the court.
Roared on by fans, Swiatek held her nerve in a tense 12th game that had three deuces, before suddenly moving through the gears to quell the challenge of the free-swinging Cristian in nearly two hours.