World number one Simona Halep made a slow start to her French Open campaign on Wednesday with a 2-6 6-1 6-1 first round victory over American Alison Riske.

The Romanian was runner-up at Roland Garros last year as she bids to go one step better this time around.

Halep had to fightback after losing the opening set by two breaks in a rain-delayed opener in Paris.

The two-time French Open finalist is still yet to win a Grand Slam despite topping the WTA rankings for the past seven months but showed her class in the final two sets by dropping just two games in total.

Alison Riske made the better start of the two players in a match that was originally scheduled for Tuesday but held back due to bad weather in the French capital.

The world number one hit 16 unforced errors in the opening set alone before winning nine of the next 10 games to take control of the match and ultimately book her place in the second round, that included a 28-minute deciding set.

Simona Halep will face American Taylor Townsend in the second round.