New York :Juan Martn del Potro, Robin Soderling and Tomas Berdych all stand at least 6 feet 4 inches. Each bombards opponents with powerful ground strokes from the baseline. Each moves, when healthy, with speed and athleticism atypical of men their size.
Each also toppled Roger Federer in Grand Slam play in the past year, three defeats on three surfaces -- United States Open (del Potro), French Open (Soderling) and Wimbledon (Berdych) -- highlighting the evolution of men's tennis, a game in which the tall and mighty once survived on serve alone.
"That's what you have to do against Federer," said Justin Gimelstob, a Tennis Channel commentator and retired pro. "You have to put pressure on him. You have to put power into his backhand. You've got to match his athleticism and movement. That's where the sport is going.
"I call those players the new hybrid."
Pros were once divided more easily into two categories: big men who pummeled tennis balls but moved clumsily, and smaller men who played with elegance and artistry, a backhanded way of saying they lacked a certain power. There were exceptions, sure. Now, few players hit harder than the 6-foot-1 Rafael Nadal.
But he is surrounded by the evolution, by del Potro (6-6 and recovering from injury), Berdych (6-5) and Soderling (6-4), and by the next wave of American talent, players like Sam Querrey (6-6) and John Isner (6-9). They are elite young pros -- or the makings of an undersize N.B.A. frontcourt.
This trend, an infiltration of taller, stronger players with athleticism to match, mirrors developments in women's tennis and changes across sports. It also forecasts a different game. Even Nadal recently said that he must play more aggressively to contend at important tournaments, and he did so in winning the French Open and Wimbledon.
"These guys all have the ability to dictate whether they're going to lose a match," said Darren Cahill, a retired player turned ESPN analyst. "They all hit the ball a ton. They all move gracefully. Tennis has become more of a big-man game."
Gimelstob noticed the change before he retired in 2007. In a recent interview, the 6-5 Gimelstob described taller players like him as "big and slow" back then. Boris Becker, nicknamed Boom Boom, was once regarded as a hulking force on tour, but he would not stand out for size alone today.
In an interview at Wimbledon, Becker said conditions forced taller players in his day to boom serves, approach and hope for an upset. Such players were rare.
Now, men of similar size can play defensive tennis and strategic tennis and win points from the baseline. Becker, like many, said technology played the most important role.
"The boys are so powerful off of the baseline now that they don't have to come to the net to finish points," he said. "That's the reason we went to the net. To finish the point. Nowadays, even the big guys can hit winners four feet behind the baseline."
But that explains only part of the evolution. As far back as when rackets switched from wood to graphite, purists have fretted that power would take over tennis. Artistry ultimately won out for years.
More recent advances in string and racket technology were also influential, as extra spin helped shots once seemingly headed for the fence land safely within the lines. As Cahill conducted a recent interview, Berdych walked down the hallway at the Rogers Cup in Toronto. Cahill nodded in his direction.
"Look at how big he is," Cahill said. "He can stand behind the baseline and take huge swings. With that ability, players can unload on shots you never could have 20 years ago, 15 years ago."
Lately, Federer is often asked to defend his place in the modern game. Perhaps his recent inconsistent results speak more to depth than any decline on his part.
As Federer said in Toronto, serves of more than 200 kilometers an hour (about 125 miles an hour) once registered as big. Now they are normal.
Average second serves, meanwhile, have increased by about 25 m.p.h., in Federer's estimation. Returns have therefore also gotten faster, and with fewer players approaching the net, placement has become less important.
Racket technology, Federer added, allows for different angles, shorter and more varied for shots smacked at maximum speed.
All of which, Federer argued, lowered the margin for error.
"Guys are hitting the ball bigger than ever," he said. "I'm very good, but I don't have the margins like maybe exist in women's tennis that you can just come out and dominate an opponent every single time. That just doesn't happen in the men's game."
Federer recently told the BBC that he wants to win 20 Grand Slam championships, or four more, before retiring. He said he did not worry that the increased emphasis on power would eventually phase him out.
Paul Annacone, the coach who started working with Federer recently, described him as a forward thinker more than willing to adapt. He pointed to the championship Federer secured in Cincinnati and his "commitment and belief."
Cahill even argued that the serve-and-volley style considered a tennis dinosaur in some quarters would eventually return. Such is the cyclical nature of all sports, including this one. Others advocate simpler rackets and strings, a limit to evolution.
Perhaps tennis's next superstar will stand tall and serve big and play with a Federer-like elegance.
"There's still room for flair and artistry and playing a game that's going to confuse people," Cahill said. "Federer has proven that, time and time and time again. Even with the new string technology, which has been around for 10 years. He still won 16 majors."
Regardless, the next wave has arrived. Call it the hybrid generation.