Who will break up the big three?

WIMBLEDON, England -- For eight years, the men's game has been defined by dominance. First Roger Federer took over the sport by winning three of the four Grand Slams in 2004. Then Rafael Nadal came along in 2005 and won his first major title at the French Open. Finally, Novak Djokovic broke through at the 2008 Australian Open, and emerged as a force in his own right last year.

Their collective dominance in the majors has only increased. Federer won five out of eight Grand Slams until Nadal came along. The two of them won 17 of the next 18, interrupted only by Djokovic. And coming into this year's Wimbledon, the trio has won 32 of the past 36 majors -- and 28 of the past 29.

"It's interesting. It shows how solid we've been over the last years, how hard it is to break through, but how hard it is to stay at the top," Federer said Monday.

"It is incredible to what degree we have been able to not only win the Slams, but also in the Masters 1000s," he continued. "You can include Andy Murray to those as well because he's won a ton of those. It seems like it's really hard for other players to break through, really, on a Slam level or a Masters 1000 level."

Djokovic, Nadal, Federer and Murray have won 20 of the past 21 Masters Series events.

Who will be the next to join them? Can anyone? The bar has been set so high, so rigid and so constant that the idea of anyone else winning a Grand Slam seems far-fetched. Murray has, at times, managed to get close enough for a victory to be feasible, even anticipated, but looks a bit bruised and battered by the attempt.

And forget about winning the whole thing -- even winning a single match against the top three at a Slam has become a feat. They rarely lose to anyone but each other -- only once each in the past two years.

"I put it down to hard work, talent, and the mental and physical abilities to also win on poorer days," Federer said.

That's a lot of factors, but an affirmation of just how high the mountain is. In growing succession, Federer, Nadal and Djokovic have set new standards of play, blurred the line between defense and offense, narrowed their weaknesses and have shown the steadiness, endurance and adaptability to outlast tennis' long, grueling seasons and surface changes.

For those who want to follow in their footsteps, it's a daunting climb.

"They've worked and they've built themselves a really good base and a really high standard," said 20-year-old American Ryan Harrison. "They don't panic and they don't overplay. They play their game and stay with it and don't give you anything. And they just consistently over a period of time will break you down."

But he's game for the challenge, which, ready or not, comes in the form of top seed Djokovic in the second round Wednesday. Harrison believes he's ready.

"I've played a lot of big matches against a lot of good players on big courts," he said. "And I'm playing the best tennis of my career right now. So I know if I go out there, I'm going to give myself a real chance."

Few others will. Though precocious by today's standards, Harrison is still developing his all-around game and learning how to manage the emotion of a match. But he has shown a taste for the big occasion and, unusual for a young player, he likes to play on grass.

"I don't like that nothing-to-lose mentality," Harrison said. "I've never told myself in a match, 'Oh, you know, I can just swing out because if I lose this one, everyone expected me to, he's No. 1 in the world,' all that stuff. I'm going to be playing with my expectations of myself. And I don't really care if anyone thinks I'm going to win or not."

Harrison quickly has become known for being articulate beyond his years off the court, as well as having trouble controlling his frustration on it. He knows that he will have to try to produce something special, which could result in more errors. But he also wants to avoid letting Djokovic set the pace like in their previous encounter last year at Cincinnati, where Harrison lost in straight sets.

"If I'm taking a risk and playing a tight shot into a tight corner, it's not because I want to. It's because I've been forced to," Harrison said. "I'm sure there's going to be times when he's play[ing] some fantastic tennis, and I have to keep my composure and step up."

If Harrison can make an impact on the defending champion, it'll be a big step forward on the long, long route to the top that the top three have created.