New York, USA, 29 August 2012 | AAP

Andy Roddick says the days of Lleyton Hewitt-like prodigies dominating men’s tennis may be over as Roger Federer leads an unprecedented revival of the thirty somethings.

A record 33 players aged 30 or over make up the 128-man draw at Flushing Meadows, headed by 31-year-old Federer, the second-oldest men’s world No.1 in history.

Hewitt qualified for the Australian Open at 15, won his maiden ATP Tour event at 16, a Davis Cup at 18, his first grand slam title at 20 and was the youngest-ever year-ending No.1 at 20 years and eight months in 2001.

Marat Safin was also 20 when he reached the summit, while Roddick was 21 when he briefly reigned almost a decade ago.

Now 19-year-old Bernard Tomic, currently ranked 43rd, is the only teenager in the top 100.

But Tomic, who climbed to a career-high 27th in June, has yet to even claim his first ATP title, though he did win last year’s Kooyong Classic exhibition event in Melbourne.

“You don’t see a lot of guys like Lleyton, who was winning it at whatever it was – 15 or 16 – now,” Roddick said after setting up an intriguing battle of the generations against Tomic at the US Open.

“Rafa (Nadal), I feel like was fully built when he was 17. Beyond that, I feel like it takes a little while to develop.

“It’s a physical nature. I don’t think kind of the age thing that we have been talking about the whole time, I don’t think that’s a coincidence.

“The game has become a lot more physical. I think you have to be a fully grown human to deal with kind of the ins and outs of the physical grind.

“That’s probably why you’re seeing what you see now. You have to kind of be able to kind of take a beating week in and week out.

“It’s not as much about shot making now as it is about kind of movement and that sort of thing.”

Roddick, who beat another talented youngster in fellow American Rhyne Williams in his Flushing Meadows opener on Tuesday, has never faced Tomic before.

“Obviously he’s been talked about for a while now and he has a kind of very good feel for the game,” Roddick said.

“It will be tough.”