Iga Swiatek began the defence of her French Open title with a dominant 61-minute victory over qualifier Leolia Janjan.
The world number one is trying to become the first woman since Justine Henin in 2007 to win three consecutive French Open titles.
And the Pole started well on the second day at Roland Garros with a comfortable 6-1, 6-2 victory.
This will set up an intriguing match-up with fellow four-time Grand Slam champion Naomi Osaka, who is returning from maternity leave.
“I feel like I'm at home here,” Swiatek told the Paris crowd.
“I hope to be here as long as possible.”
Swiatek is coming off consecutive clay-court titles in Madrid and Rome and is the favorite to win in Paris.
After a dominant first set, Swiatek conceded a break in the second but raised her level when she needed to to win.
“I think it's too early,” Swiatek said when asked if she felt like the “Queen of Clay,” a play on the nickname of 14-time men's singles champion Rafael Nadal.
“I'm really proud of my accomplishments and it's always been my favourite surface.”
Rain called off much of the action on Monday, but Wimbledon champion Marketa Vondrousova dominated Spain's Rebekah Massarova 6-1, 6-3 in the morning.
Ons Jabeur, still searching for his first Grand Slam title after three runner-up finishes, defeated American wild card Sasir Vickery in an equally brutal fashion, 6-3, 6-2.
U.S. Open champion Coco Gauff and Britain's Harriet Dart are also scheduled to play on Monday.
