It was then-28-year-old Stan Wawrinka who snapped the streak of 16 straight Grand Slam titles by Djokovic, Roger Federer, Rafael Nadal and Andy Murray when he won the Australian Open in January. The only other men in the U.S. Open field who have reached a major final in the last five years are 32-year-old David Ferrer and 28-year-old Tomas Berdych.
The U.S. Open starts Monday with Djokovic, Murray, Wawrinka, Maria Sharapova and Venus Williams among the big names on the court. The player with the most impressive performance leading to this tournament was 29-year-old Jo-Wilfried Tsonga. Tsonga, the runner-up at the 2008 Australian Open, beat Djokovic, Murray, Dimitrov and Federer to win the title at Toronto this month.
As the sport became more physical, Grand Slam titles became less likely not only for teenagers but for players in their early 20s.
"Everybody realizes that you're reaching your peak physically maybe a little bit later and then they're staying there longer, because they have the technology and they're more systematic about their training," said Patrick McEnroe, the U.S. Tennis Association's general manager of player development.
So a group of players not that young by tennis standards has gained little experience of playing in the highest-pressure moments. The oft-repeated stat is that the Big 4 have won 36 of the last 38 Grand Slam titles.
Contrast that to the five years before Nadal won his first major championships at the 2005 French Open to start that streak. As Pete Sampras' reign was ending and Federer's beginning, 12 different players won the 20 Grand Slam titles; for six of them, it would be their only major championship.
Now, it's daunting not just to win championships but to even get close to them.
"It's definitely been a tough time for everybody else trying to break through," Raonic said.
Especially younger players. Of the eight other men to play in Grand Slam title matches since the 2006 French, only Tsonga and Juan Martin del Potro were under age 24.
Djokovic and Murray were born a week apart in 1987; Nadal is less than a year older. If they can stay healthy certainly a big "if" with Nadal the logjam at the top could stick for a while.
U.S. Open, first round
• 11 a.m., ESPN
• 4 p.m., ESNP2