She is playing at a Slam for the first time since winning the Australian Open in 2017 when she was already nearly two months pregnant. Future launches have inspirational messaging written right on to them, so wearers can be reassured throughout the day - "It's just a friendly reminder: I'm strong and I'm attractive", says Williams. "I'm just happy to take it a day at a time".
Halep said in her post-match interview that she struggled initially against the left-hander's shots with topspin.
The tennis star is now participating in the French Open, her first major tournament since giving birth, and has her sights on conquering Wimbledon this July.
Nadal racked up his 80th win in Paris by seeing off Italian lucky loser Simone Bolelli 6-4, 6-3, 7-6 (11/9).
Sharapova, playing the tournament for the first time in three years after missing 2016 through a doping ban and last year when she was refused a wildcard, battled from a 0-3 deficit in the final set to beat Dutch qualifier Richel Hogenkamp 6-1, 4-6, 6-3.
Fighting spirit: Maria Sharapova celebrates after victory against Netherland's Richel Hogenkamp.More news: Street Fighter 30th Anniversary Collection Out Now
Barty's game plan to move Williams from side to side in the hope of exhausting the underdone champion in just her sixth match back since giving birth last September initially paid dividends.
This time, she opted for a denim mini-skirt, knee-high black boots and a studded black blouse.
Williams, who is chasing her 24th Grand Slam title, returned to tennis earlier this year after giving birth to her daughter, Olympia.
The world No.25 looked like suffering her third consecutive first-round defeat at Roland Garros before turning the match around after a 45-minute rain delay.
Former world number one Chris Evert grasped the nettle more firmly.
He quickly levelled at 3-3 on Tuesday, saved four break points in the eighth game before saving four set points in the breaker.
Nadal, chasing a record-extending 11th men's title, will play Guido Pella in the second round.More news: Abramovich's Chelsea suspends $1.3b stadium plans
"I can't believe how much went wrong on my way to meeting her".
Sharapova also survived a serious scare to claim a 6-1, 4-6, 6-3 victory over Hogenkamp, ranked 133.
Sharapova, the 28th seed, will face Croatia's Donna Vekic in the second round.
And it showed against Barty, after it had looked initially as if the American would be exiting at the second stage - something she has not done in a Slam since the 2014 tournament at Roland Garros.
And now she will go into her first Grand Slam match in 497 days without a single warm-up match on clay with all of her competitive tennis in 2018 having come on hard courts.
"She's a genuine champion".
"It felt really good", said Australia's 17th seed.More news: Xiaomi Intros Mi Band 3 With Touch-Sensitive OLED Display