Current wisdom says brutal world of men's tennis is too tough for newcomers like Sock and that they must bide their time before breaking through in their mid 20s.
The 35-year-old Haas's incredible resurgence supports that logic, as does the fact that there were 30 players aged 30 and over in the main draw, compared with just three teenagers and nine aged 21 and under.
With Novak Djokovic the youngest member of the top four already 26 and 17-times grand slam champion and world number three Roger Federer now 31, it seems the days of teenagers challenging for major silverware are on hold.
However, Sock, who went through his entire high school tennis career without losing a match, proved against seasoned 30-year-old Guillermo Garcia-Lopez that there is plenty of emerging talent on the horizon.
Add the names of 19-year-old Frenchman Lucas Pouille and Australian upstart Nick Kyrgios, 18, and the second round will be well represented by the young guns keen to make their mark.
Kyrgios dismissed wily 34-year-old Czech Radek Stepanek on Monday while Pouille, who toughened himself up by playing obscure tournaments in Vietnam this year, accounted for American wildcard Alex Kuznetsov in convincing fashion.
Haas showed his enduring quality in beating Guillaume Rufin but will be wary of the threat of Sock, who showed admirable maturity to deal with the weather and an obdurate Spanish claycourter in his French Open debut.
Sock, who reached the third round of the U.S. Open last year and won the mixed doubles there in 2011 with Melanie Oudin, said he was relishing the challenge, having already sharpened his claycourt skills during three qualifying rounds.
"I practise with him a lot actually in Los Angeles and at tournaments," Sock, who like former world number one and idol Andy Roddick was born in Nebraska, told reporters.
"He's obviously a very good player and made a great comeback to be top 15 now in the world. I'm just going to go out there and have fun and compete hard and see how it goes."
A livewire character like Roddick, who once said of him "he sounds a little like an 18-year-old I knew once upon a time," Sock said he hoped his match with Haas would be on a show court.
"I like playing in front of people, I like the big stages. I mean, the more the merrier," he said.
Next up for Pouille, a little behind Sock in his development and ranked 310 in the world, is Bulgarian Grigor Dimitrov, the 28th seed who at 22 is finally beginning to release the potential that was clear as a teenager.
Dimitrov's steady rather than spectacular rise up the rankings since joining the Tour armed with a Wimbledon junior title and a style similar to Roger Federer, illustrates just how tough it can be to make the transition from junior to senior.
Pouille's progress is being closely monitored in France but he says the expectations being placed on his shoulders are not a problem. "I try not to pay that much attention to it," he said.
"Just keep moving on. Today I could be among the best in my age group, but you never know what the future holds."
A match against 28th seed Dimitrov will offer further evidence of his potential.
"He's in fine form. He almost beat Nadal. He's playing very well," he said. "But at end of day, it's a game of tennis. Even though he is the favorite, I will be entering the court with a desire to win, and that's it."
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