PARIS (AFP) - Novak Djokovic took his unbeaten record in 2011 to 38 wins on Monday before Grand Slam king Roger Federer demonstrated to the unstoppable Serb that he is still a French Open force. Second seed Djokovic enjoyed a 6-2, 6-1, 6-3 dismissal of hapless Dutchman Thiemo De Bakker in the first round before 16-time Grand Slam title-winner Federer romped to a 6-3, 6-4, 7-6 (7/3) win over Spain's Feliciano Lopez. Also going through on a sweltering day at Roland Garros was former US Open champion, and 2009 semi-finalist here, Juan Martin del Potro, a winner in four sets against Croatia's Ivo Karlovic. But sixth seed Czech Tomas Berdych, a semi-finalist last year, wilted in the heat, losing in five sets to French qualifier Stephane Robert, the world number 140. One day after his 24th birthday, the red-hot, world number two Djokovic comfortably saw off the 71st-ranked De Bakker in just 92 minutes. Djokovic, who is likely to depose Rafael Nadal as world number one by the end of the tournament, is also favourite to snatch the Spaniard's French Open title, having seen off his rival in the Madrid and Rome clay court finals. His win on Monday took him to within four victories of equalling John McEnroe's 1984 record for a winning season start of 42 triumphs. "It's my favourite Grand Slam, even though I haven't won it yet," said Djokovic, a semi-finalist in 2007 and 2008. Djokovic, the Australian Open champion, who has seven titles under his belt already this year, will play either French wild card Benoit Paire or Romania's Victor Hanescu for a place in the last 32. World number three Federer, playing at his lowest seeding in eight years at a Grand Slam, is taking part in his 46th consecutive major. He had won all his previous eight matches against Lopez but would have been wary of an opponent who had a match point in their last encounter at the Madrid Masters second round earlier this month. However, he was in little danger on Monday, cruising to victory against a player who has now lost eight times in the first round in 11 Paris visits. Federer will next tackle French wild card Maxime Teixeira for a place in the last 32. Argentina's del Potro overcame a first-set blip to defeat Karlovic. Del Potro, who was a doubt for the tournament because of a hip injury, having missed the 2010 event due to wrist surgery, claimed a 6-7 (7/9), 6-3, 7-5, 6-4 win. The 25th-seed hit 21 unforced errors to Karlovic's 42 and will next face Slovenia's Blaz Kavcic, with Djokovic a potential third round opponent. "I'm not thinking about Djokovic," said Del Potro. "Kavcic is playing well. I'll need to play good tennis, probably better than today." Top seed Nadal, bidding to equal Bjorn Borg's record of six French Open titles, gets his campaign underway today (Tuesday) against John Isner of the United States. Berdych, a semi-finalist last year and the Wimbledon runner-up, slumped to a shock 3-6, 3-6, 6-2, 6-2, 9-7 defeat against Robert, despite having had a match point at 5-4 in the final set. It was 31-year-old Robert's first career win at Roland Garros and just his second victory in eight Grand Slam appearances. French ninth seed Gael Monfils and American number 10 seed Mardy Fish both went through, as did Djokovic's Davis Cup-winning team-mate Viktor Troicki, the 15th seed, and Russian 12th seed Mikhail Youzhny. In the opening match on center court, defending champion Francesca Schiavone beat Melanie Oudin of the United States 6-2, 6-0. Schiavone, who last year became the first Italian woman to win a Grand Slam singles title, won four straight games in the first set after being broken early by her 19-year-old American opponent. The fifth-seeded Schiavone, who had 25 winners to Oudins six, and then won seven straight games to reach the second round. Last week, Schiavone had her best result of the season, reaching the semi-finals at the Brussels Open. Vera Zvonareva Agnieszka Radwanska, Daniela Hantuchova and Roberta Vinci of Italy also advanced, while Nadia Petrova and Klara Zakopalova of the Czech Republic lost.