Roger Federer has made a career, and untold riches, out of an assured presence that meant his matches were half-won before they even started.
  
Not so against the new breed of young upstarts, who are coming into their prime as Federer's powers wane along with the famous fear factor.
  
France's Gilles Simon, 23, said he has no "complex" about playing Federer, and proved it by beating him for the second time this year at the Tennis Masters Cup.
  
"I defeated him once in Toronto, so it was easier to finish the match. I had no complex when I served in the last game. And, for sure, it was one of the best victories of my career," he said.
  
Simon is one of a group of younger players who have conquered the 13-time Grand Slam champion this year, including Andy Murray, Novak Djokovic, Ivo Karlovic and Rafael Nadal.
  
Federer, 27, has slipped slightly from the heady heights he has occupied since 2004, losing his 237-week stay at number one and his five-year Wimbledon streak.
  
His 14 defeats this year have come against nine different players, with old stagers Andy Roddick and James Blake also taking grateful advantage of the dip in form.
  
Simon and Murray are among four debutants at the Masters Cup, along with Jo-Wilfried Tsonga and Juan Martin del Potro, providing a new challenge for the four-time champion.
  
"The better you play, the better he plays," Federer said of Simon.
  
"He's quite a unique player and he makes you work hard and runs very well. Yeah, he's unusual to play against."
  
Federer said he would draw on his experiences of last year, when he also lost his first match before bulldozing his way to a second successive title.
  
"Last year was difficult. I think this year will be more easy because I've already gone through it just a year ago. I think that's going to help me out," Federer said.
  
For Simon, it was proof that his July victory over the then number one was no accident. The Frenchman said self-belief was the key as he came from a set down to win 4-6, 6-4, 6-3.
  
"I didn't wait until the beginning of the third set to think that I had a chance to win. Because if you come on court and think you have no chance to win, you just lose in two sets," Simon said.
  
"So I really started to believe in myself and my chance to win at the beginning of the match."
  
The elite, 4.45-million-dollar season finale features an eight-man field who each play three group matches to qualify for the semi-finals.