World number two Kim Clijsters made heavy weather of her first French Open appearance in five years, overcoming Anastasiya Yakimova 6-2 6-3.
Clijsters conceded a break on the verge of victory, before finally disposing of the Belarusian in 80 minutes.
The two-time finalist will face the Netherlands' Arantxa Rus next.
Rome Masters winner Maria Sharapova and fourth seed Victoria Azarenka also progressed, but former champion Ana Ivanovic suffered a first-round upset.
Clijsters, the Australian and US Open champion, had not played at Roland Garros since her 2006 semi-final defeat by Justine Henin.
Three tournaments went by during her break from the game, while she was absent last year through a foot injury.
The Belgian, who has missed another two months of action in the build-up to this year's event, admitted she was still getting reacquainted with the surface.
"I felt that I was moving aggressively but didn't always go to the lines as much as I would like to," she said.
"I was trying, but I was kind of just not on target as much as I would like to be."
Sharapova needed only 56 minutes to brush aside Croatian Mirjana Lucic and reach the French Open second round.
The seventh-seeded Russian, a semi-finalist at Roland Garros in 2007, broke for a 4-3 lead in the first set before taking nine successive games.
Lucic, ranked 94, crumbled and the errors soon mounted as Sharapova wrapped up the 6-3 6-0 victory in emphatic fashion.
Sharapova, won the Wimbledon title in 2004, the US Open in 2006 and the Australian Open in 2008, will face France's Caroline Garcia for a place in the last 32.
Also advancing to the second round was China's sixth-seeded Li Na, who overcame a stumble in the second set to progress 6-3 6-7 (6-8) 6-3 against Barbora Zahlavova Strycova of the Czech Republic.
Fourth seed Azarenka made more leisurely progress as she dispatched the Czech Republic's Andrea Hlavackova 6-3 6-3.
Yanina Wickmayer, seeded 21st, was similarly ruthless in seeing off Romania's Monica Niculescu 6-0 6-3, as 15th seed Andrea Petkovic had to save three set points to prevent 6-4 7-6 (7-3) win over Bojana Jovanovski heading to a decider.
Unseeded Swede Johanna Larsson, ranked 64th in the world, surrendered the second set to love, but bounced back to upset the Serb 7-6 (7-3) 0-6 6-2.
Ivanovic was in tears after the defeat as she explained that a wrist injury, the latest in a run of health problems, had restricted her play.
"It is very frustrating. It's inflammation of the wrist but I didn't suffer it playing, I woke up with the problem. The bone has slipped and has caused friction. I'm very upset," she said.
Australian 24th seed Jarmila Gajdosova swept aside France's Virginie Razzano in business-like style with a 6-3 6-1 win.
Razzano's defeat on the Philippe Chatrier court came eight days after her coach and fiance Stephane Vidal died of a brain tumour.
"I grabbed all my courage. I don't have much. I'm very fragile," said Razzano.
"I feel lonely, and even though there are many people around me supporting me I still have the strength in me that keeps me standing up and moving on step by step."
Razzano confirmed that she intends to play at the AEGON Classic in Birmingham in June as she agreed with Vidal before his death.