CHARLESTON, SC, USA — Monica Puig was the first of two main draw winners as the Volvo Car Open got underway in Charleston on Monday, as Katerina Siniakova was forced to retire with a back injury in the final set.

Siniakova received medical attention earlier in the match, and retired as the match hit the two-hour mark, trailing 6-4, 2-6, 1-4 to send the Puerto Rican in to the second round.

“It’s always nice to come back and play on the clay again — unfortunately she had to retire there in the third set,” Puig said after the match. “I thought it was some pretty good, high-quality tennis up until that point.

“She was definitely holding, clutching her back a little bit there in the second set, so I was obviously a little bit aware something was going on. I had to try and keep focus because sometimes when a player is feeling a little bit of discomfort, they start hitting the ball hard, going for their shots a little more. I had to really focus and pay attention.”

Puig, who reached the third round in Charleston last season, fell behind early as Siniakova broke in the first game and rode the advantage to a one-set lead. She flipped the script in the second set, breaking Siniakova at the first opportunity to open up a 3-0 lead en route to sending the match to a decider. While the Czech fought through valiantly in the decider, she dropped serve in the fourth game and was unable to continue much further from there.

.@MonicaAce93 is first through to @VolvoCarOpen Second round!

Siniakova retires due to injury pic.twitter.com/xcJH4OUG9S

— WTA (@WTA) April 3, 2017

The Puerto Rican played her first WTA main draw in Charleston in 2011 after coming through qualifying and the World No.40 is eager to use one of her most successful tour stops as a springboard on the road to the French Open

“I love the clay. I really enjoy playing on it. Not so much the green clay because you don’t really notice that you’re on clay as much as the red clay — I love getting off the court and seeing I’m all dirty!” she joked.

“You don’t really have to change up your game style, but you have to adjust to what you have to do as far as tactics and things like that,” Puig assessed, as she’ll face the winner of the match between Daria Kasatkina and Danka Kovinic in the second round. “That’s what my coach and I were trying to work on coming into this clay season, just to really be smart of there.” 

Joining Puig in the second round as an early winner was Japan’s Naomi Osaka, who rallied for her first career main draw win in Charleston after dropping the first set against Johanna Larsson, 6-7(4), 6-4, 6-2.

Check out the rest of the opening round results here.