Serbian duo Novak Djokovic and Ana Ivanovic, both tipped as potential Roland Garros champions, endured struggling starts to the French Open on Sunday.
Third seed Djokovic, the Australian Open champion and Rome Masters winner, needed four sets to see off Germany's world number 64 Denis Gremelmayr 4-6, 6-3, 7-5, 6-2.
Women's second seed Ivanovic, who crumbled to defeat in the 2007 final against Justine Henin, took a first nervous step towards erasing that heartbreaking memory by seeing off Sweden's Sofia Arvidsson 6-2, 7-5.
"He surprised me a little bit. He was aggressive, took his chances and went for his shots. He deserved to win the first set," said Djokovic, a semi-finalist here in 2007, and the best player on the tour this year.
"I was ahead 5-1 in the third set, he came back to 5-5. I lost my focus so hopefully that will be the end of it."
Djokovic will now face Spanish qualifier Miguel Angel Lopez Jaen for a place in the third round.
Gremelmayr, a semi-finalist on clay in Estoril and Barcelona, took the first set after racing into a 4-0 lead before the 21-year-old Serbian levelled the tie courtesy of a break in the eighth game of the second set.
Djokovic raced to a 5-1 lead in the third set but the 26-year-old German hit back to level at 5-5 before the Serb broke back in the 11th game and then served it out.
The world number three cruised to victory with breaks in the third and fifth games of the fourth set.
World number two Ivanovic became Serbia's first Grand Slam finalist here in 2007 beating Svetlana Kuznetsova and Maria Sharapova before she fell to pieces in the final against Henin, going down 6-1, 6-2.
Since then she has also finished runner-up to Sharapova at the Australian Open.
But it wasn't 20-year-old Ivanovic's most convincing display on Sunday.
After easing through the first set, she then had to save break points in the fifth, seventh and ninth games of the second before seeing off the 24-year-old Swede whom she had also defeated at the same stage here last year.
"If I reach the final again I'll perform a lot better than I did last year. That was a great experience and I don't regret it," said Ivanovic whose build-up to Paris wasn't helped by a shock first round defeat in Rome where she was top seed.
"This year I'm in a different position to last year. Then I had only just broken into the world top 10 and there was less pressure. Now I am number two in the world so I have more expectations."
Ivanovic will now face the Czech Republic's Lucie Safarova for a place in the third round.
However, another Czech was already packing her bags after 15th seed Nicole Vaidisova, a semi-finalist in 2006, slumped to a 7-6 (7/2), 6-1 defeat to compatriot, and best friend, Iveta Benesova.
Vaidisova's defeat was her sixth in a row this year leaving her without a win since the first round in Dubai three months ago.
Meanwhile, Argentinian sixth seed David Nalbandian, widely regarded as one of the few players capable of shattering triple champion Rafael Nadal's pursuit of a fourth successive title, saw off compatriot Carlos Berlocq 6-2, 6-4, 6-1.
Nalbandian, a semi-finalist in 2004 and 2006, holds a 2-0 career record over Nadal and could meet the Spaniard in the quarter-finals.
He next faces French wildcard Jeremy Chardy.
American seventh seed James Blake, who has never got beyond the third round, saw off German veteran Rainer Schuettler 6-4, 6-1, 7-6 (7/3) and will tackle either Simon Greul of Germany or Ernests Gulbis of Latvia.
Later Sunday, former triple champion Gustavo Kuerten, whose career has been devastated by a chronic hip injury, will play what will probably be his final ever match when he returns to his beloved Philippe Chatrier Court to take on French 18th seed Paul-Henri Mathieu.
Women's 2002 champion Serena Williams is also due on court to face fellow American Ashley Harkleroad.