PARIS, France - A day later than anticipated, World No.1 and two-time runner-up Simona Halep got her French Open campaign underway on Court Philippe Chatrier on Wednesday, and the Romanian held off an upset bid from American Alison Riske to move safely through to the second round.

The last of the first round matches to take the court, Halep and Riske were scheduled to play on Tuesday, but were postponed until the first match on for Wednesday thanks to rain and extended matches on Paris' center court. 

Once in action, the World No.83 and runner-up at the Nürnberger Versicherung last week had an upset on her mind, as she raced out to a 5-0 lead en route to winning the first set, but ultimately, Halep battled back for a 2-6, 6-1, 6-1 victory in one hour and 34 minutes. 

"I had a slow start because it's always tough to start this tournament. It's a pleasure to come here and to play, so always I feel nervous at the beginning," Halep said after the match.

"It was good that I came back so strong. I just didn't think about the result or about the match. I just wanted to relax my arms, because I was moving pretty well also at the beginning, but my arm was very tight and I couldn't hit the ball as I wanted.

"Then it was much easier, and I felt really well in the end of the match, and that's the most important for now."

The Romanian littered the stat sheet with 16 unforced errors to just four winners in the opening set, as Riske's calculated, flat hitting paid off to the tune of 13 winners to just 10 unforced. 

However, Halep slowly worked her way into the match after saving a bagel from two points away in the opening set, and though she fell behind, she never proved in much danger over the course of sets two and three. 

The World No.1 lost just five points in the first five games of the second set to assert more authority on the encounter, and later won the first three and last three games of the decider to avoid a first-round exit in Paris for the first time since 2013.

Despite the early hole, Halep ended the match with 20 winners to 28 unforced, giving her 16 winners to 12 miscues over the second and third sets.

Conversely, Riske was unable to keep up her hot start, as she struck just four winners after the first set for a total of 17, and accumulated 33 unforced erros overall. 

Halep will next face another American in wildcard Taylor Townsend in the second round, after she defeated fellow wildcard in France's Myrtille Georges on Tuesday.

"It's different, because she's lefty, so it's going to be different match," the World No.1 said.

"If I remember well, I played her in Cincinnati. I remember that she's solid. She hits strong. I have just to move her, to be aggressive, and to play like today, but just the second set and the third set."