[gallery size="medium" td_select_gallery_slide="slide" td_gallery_title_input="Thiem, Zverev aiming to upset old guard" ids="148139,148140,148141"] PARIS — The old guard may still be winning the major trophies but the youngsters are creeping up on them. Rafael Nadal, Roger Federer, Novak Djokovic, Andy Murray and Stan Wawrinka have dominated the Grand Slams since 2005. However, a couple of dark horses are hoping to spring a surprise at the French Open, which starts Sunday. The 20-year-old Alexander Zverev beat Novak Djokovic to win the Italian Open last Sunday, while the 23-year-old Dominic Thiem also impressed in the tournament, defeating Nadal. "I think that Rafa is the big favorite," Thiem said Friday. "Novak is coming, for sure behind him. And then Murray, you never know. He's such a big player. He can also play amazing here. "And after these three I think there are some players who can go very deep here who can make big surprises and to these players I count Sascha (Alexander Zverev) and myself." This is the first week in the 40-year-plus history of the ATP computer rankings that the top five men are all 30 or older. However, the seventh-ranked Thiem doesn't see that as failure by the younger players. "They are so big players that it's I think normal that they are still so good with a little bit older age," Thiem said. "But I wouldn't say that the younger players, they didn't make it. I mean there is Milos (Raonic) or Kei (Nishikori) that have been in the top 10 for a very long time. "Everybody should know how tough it is. Because they didn't win a Slam yet, it doesn't mean that they didn't make it because obviously the Big 4 are so strong that it's in this period really tough to win a big title." Nadal will be favorite to claim a 10th title at Roland Garros, on his favorite surface. Thiem has already faced Nadal three times this year, losing finals in Barcelona and Madrid before beating the Spaniard in Rome 6-4, 6-3. "The win over Rafa was of course a big thing for me," Thiem said. "I played the best player on clay three times in three tournaments. I learned a lot ... so I think I prepared well for this tournament. Thiem reached the French Open semifinals last year, losing to eventual champion Djokovic. If the Austrian gets to the same stage this season he will most likely face Nadal again, and he knows the 30-year-old Spaniard is the one to beat. "100 percent he's the big favorite. He's on the top to win here," Thiem said of Nadal. "Of course I think he's back at his best this year, and then also he won nine times. So he knows how it works to win here. "I will think he will try everything to win Le Decima, I think it will be very unique in tennis to win a Grand Slam title 10 times. It's pretty crazy, I guess. So 100 percent he's the one to beat here and the big favorite." Nadal, who retired last year before his third-round match with a wrist injury, has a 72-2 record at the clay-court major and is the only player with nine trophies from one Grand Slam tournament. This season, he has been the dominant player on clay, winning 17 straight matches on his favorite surface and three consecutive titles before Thiem halted his run. Long dominated by youth, women's Tennis pushed the boundaries of experience at the Australian Open in January when the combined age of the two finalists, Serena and Venus Williams, topped 70 for the first time. With five of the top 10 in the current rankings aged 28 or older, form suggests another pair of seasoned campaigners could contest the title match here.