"I sometimes struggle at the beginning to find rhythm" - Swiatek on playing in her first night match in Paris

Despite lifting the Roland Garros trophy last year, Iga Swiatek was faced with the challenge of playing in her first night session match on Court-Philippe-Chatrier as she took on Marta Kostyuk in the round of 16 on Monday.

Nonetheless, the defending French Open champion was able to overcome her younger opponent, sending the 18-year old Ukrainian packing with a 6-3 6-4 victory.

"Playing the night session... is always hard, because you have to change the whole rhythm of the day, change the routines," Swiatek said after the match. So still, even though I played many night sessions right now, I sometimes struggle at the beginning to find the rhythm and to see the ball properly with the lights, not with the sun.

"You just have to adjust to that, because we both have the same conditions. It's going better and better every match, but still, I need some more experience."

The eighth seed was pushed in the first set, as six of the first nine games went past deuce, with Swiatek having to break back after losing her second service game. However, the 20-year old relied on her relatively young experience and competitive spirit to escape with the win.

I like being tested because it keeps me constantly on my toes," revealed Swiatek. "It just keeps you focused all the time, because you don't have that flow, so... you have to work all the time.

"With that flow, you sometimes can seem surprised that, 'Hey, something is not good,' and then you're going to panic. But right now I'm getting tested, as you said. Still I'm moving forward, so that's even better for me."

Having won 22 consecutive sets in Paris dating back to last year, the defending champion will face Maria Sakkari in the quarterfinals. The 17th-seeded Greek eliminated last year's runner-up, Sofia Kenin 6-1 6-3 earlier in the day, to advance to her maiden Grand Slam quarterfinal.