Misfiring Venus Williams relies on some psychological warfare in Paris, while Jo-Wilfried Tsonga wins marathon contest

The five-time Wimbledon champion was broken three times by Swiss Patty Schnyder – twice to love – on Suzanne Lenglen Court. But her famed court coverage meant she broke her opponent on six occasions and ran out a 6-3, 6-3, winner.

The world No2 – who has never lifted the women's singles crown at Roland Garros – will now play either Arantxa Parra Santonja of Spain or Kurumi Nara of Japan in the second round. Williams had won all ten of her previous clashes with world No61 Schnyder and believes that gave her a psychological advantage.

"The record definitely helped me because I've been at stages of my career where I've had a one-sided record against certain players," she said. "I think it helped me a lot, especially in tighter situations, so obviously I'd like to have that kind of record against everyone."

Williams has struggled on clay down the years but has shown a marked improvement this season and she is adamant she has what it takes to lift her first French Open crown. The 29-year-old said: "I always – it goes without saying – believe I can win."

Svetlana Kuznetsova admitted nerves got the better of her as she walked out on Philippe Chatrier Court to begin the defence of her title. The Russian overcame a sluggish start to cruise past Sorana Cirstea of Romania in straight sets and set up a second-round clash with German Andrea Petkovic

Sixth seed Kuznetsova dropped the opening three games against Cirstea but then reeled off nine in a row before winning 6-3, 6-1 in one hour, 12 minutes. "I was a little bit nervous at the start, and it was a rough start for me, but I think I'm very happy about it," said the Russian, whose up-and-down 2010 was reflected in her performance.

"I managed to come back and fight for every single game. It didn't matter if I was down love-40 or 15-40, whatever it was. I was just playing as many balls back as I could."

Kuznetsova admitted her recent inconsistent run of form had been playing on her mind going into yesterday morning's match.

"The clay-court season was very important for me, and I was not showing as good results as I would like to," she said. "I deserve better than that, and I worked harder than these results. I was just concerned about when it was going to pass." Petkovic will have the honour of facing last year's winner next after beating Russia's Elena Vesnina 4-6, 6-1, 6-4.

There were two seeded casualties in the women's draw by mid-afternoon on day one. Victoria Azarenka of Belarus was the biggest name to fall, the tenth seed suffering a 6-1, 6-2 defeat against Gisela Dulko, who revealed she had outwitted her opponent.

The Argentine said: "I had a very good strategy. At the beginning, I was trying to play a very good first serve and play on her forehand, because that's her soft spot."

Top seed Serena Williams headlines today's women's action when she opens against Swiss Stefanie Voegele.

In the men's singles, meanwhile, local favourite Jo-Wilfried Tsonga laboured past unheralded German Daniel Brands to reach the second round with a marathon 4-6, 6-3, 6-2, 6-7, 7-5 win last night.

Timely drop shots were enough for Brands to unsettle Tsonga early in the match as the eighth-seeded Frenchman dropped the first set before gradually finding his stride to set up a second-round meeting with compatriot Josselin Ouanna.

It was no stroll in the park for Tsonga with Brands benefiting from a string of unforced errors to level by taking the fourth set tiebreak 7-2. The German saved a match point in the tenth game of the decider, another in the 12th before bowing out when he sent a backhand long after a three-hour and 43-minute battle.

Tsonga, however, was unfazed by his slow start. "I am not worried. I played for a long time but I still have two days to recuperate," he told reporters after the match. "The fact I stayed long on the court could be a good thing because I hit many balls and helped me find some grounds (for the rest of the tournament]."

Ernests Gulbis was the highest-profile casualty after he was forced to retire against home favourite Julien Benneteau. Latvian Gulbis had been tipped as a dark horse for the title at Roland Garros after beating Roger Federer at the Rome Masters earlier this month.

The 23rd seed was unable to recover from a thigh injury which required a trip to hospital though, and retired with the score at 6-4, 6-2, 1-0 down in the first-round match on Suzanne Lenglen Court having been outplayed by his French opponent before injuring himself inadvertently performing the splits early in the second set. "I stretched my leg, my hamstrings, and I heard two cracks," said Gulbis.