The future seemed so bright. When 2003 came to a close, Andy Roddick was the youngest American male to end the year as the world's No. 1 tennis player.

Aged 21, he had just won his first grand slam title at the U.S. Open, following in the footsteps of illustrious compatriots such as Pete Sampras, Andre Agassi, John McEnroe and Jimmy Connors.

But then the drought -- another decade on, the United States is still waiting for its next male grand slam winner.

So what's gone wrong? A nation that dominated tennis from the mid-1970s is struggling to repeat those past glories -- and there is no quick solution in sight.

"I think the best athletes in other countries are playing tennis sooner than they are here," U.S. tennis great John McEnroe told CNN's Open Court.

"We've got to grab some kids that are playing American football or basketball, for example, we've got to make it more accessible, affordable."

But that's not as easy as it may sound, especially when parents of talented kids do the math.

Tennis has strong participation numbers among American school kids, but that drops off once they get to high-school age as the costs of playing skyrocket compared to subsidized sports such as gridiron, basketball and baseball.

"In junior high school, the school pays for travel expenses when they go for games. When the season is over, they pay for the expenses. Tennis you pay your own," says renowned coach Nick Bollettieri, whose academy was the breeding ground for top U.S. men's talents such as Agassi, Sampras and Jim Courier.

'Show me the money'

Potential tennis stars are also being offered higher average pay by rival U.S. sports.

Bollettieri's research has indicated that, to break even on the men's ATP World Tour, you need to be ranked at least 163rd.

He says an NFL player of equivalent status earns $1.4 million a year -- and that's without endorsements.

"When a parent looks at the financial side and sees those two figures, they say, 'Wow, and it doesn't cost us a dime,' " added Bollettieri.

"If those same parents are struggling to make a living and they look in the paper and see $25 million for a four-year contract in baseball, $80 million for LeBron James ... they look at that and the programs that develop these people, it doesn't cost them anything."

It is often argued that poverty helps breed sports stars because athletes are more determined than their wealthier peers, but seven-time grand slam champion McEnroe is unconvinced by that argument.

"Some of the guys come from tough situations who want it more -- then again, if you look at some guy from Mallorca named Nadal who presumably lives in a pretty decent situation, and some guy by the name of Federer came out of Switzerland and his parents were reasonably well off," the 54-year-old said.

Since Roddick's New York breakthrough, Rafael Nadal, Roger Federer, Novak Djokovic and Andy Murray have won 34 of the 37 grand slam titles.

"It's obvious that a lot of the other countries, their players have definitely become better, there's no question about that," says Michael Chang, the youngest player to win the French Open, as a 17-year-old back in 1989.

"The depth of men's tennis in particular has gotten deeper and deeper every year," the American told Open Court.

"When you've got guys like Rafa, Novak and Roger playing at the level they're playing, there's not going to be a whole lot of winners outside of those guys and now you can put Andy Murray inside of that group as well.

"It's been very, very difficult for American tennis to be able to follow our generation."

Success breeds success

Bollettieri believes the success of his Florida-based academy was based on offering scholarships to the likes of Agassi, Courier and Monica Seles, which later attracted other young talent from around the world including current stars such as Maria Sharapova and the Williams sisters.

"When you get good people like that at the same place, when you get 15, 20, 30 players who are the best in America and some of the best in the world, they compete," the 81-year-old said.