Birthday girl Iga Swiatek swats aside Marie Bouzkova to reach French Open last 16

Swiatek survived a major scare in the previous round when she saved a match point against Naomi Osaka before sealing a hard-fought victory, but against Bouzkova she picked apart the Czech player's serve with some precision hitting.

Swiatek is now unbeaten in 15 matches on clay, having won titles in Madrid and Rome this month, while she extended her win streak at Roland Garros to 17.

"I was waiting until after the match to feel that I have a birthday because I knew that I need to focus on my work because if I would lose, it would be a total disaster," Swiatek, who was serenaded by the fans with the "Happy Birthday" song, told reporters.

"So I'm happy that I won, and I kind of gave myself a present.

"For sure playing on your birthday, it's not so comfortable because it's eight o'clock and I have four hours (left) to celebrate. But that's the work that we have to do, we can't complain."

The defending champion showed no signs of a hangover from the three-setter with Osaka and consolidated an early break to go 3-1 up in the opening set but Bouzkova fought back from 5-2 down to give the Pole a workout.

However, Swiatek switched gears and carefully constructed her points, using the angles well to make Bouzkova run from one corner of Court Philippe-Chatrier to the other, firing 18 winners in total in the opening set.

The top seed continued to dominate in the second set as she effortlessly turned defence into offence on Bouzkova's serve, breaking twice to race into a 4-0 lead.

A desperate Bouzkova laughed in relief after one of the longest rallies of the match when a return clipped the net cord and landed on the line as the crowd roared in appreciation, a point that finally got her on the board in the second set.

Bouzkova saved a match point on her serve but she only delayed the inevitable as Swiatek sealed her progress with a searing winner down the line, her 34th of the match.

Swiatek will next play Russia's Anastasia Potapova who is ranked number 41 in the world.