New York (AFP) - The first-round exits of Steve Johnson and Ryan Harrison Wednesday saw just three American men in the second round of the US Open, the fewest in the tournament's history.
But the trio remaining from 12 home-grown contenders who started the final Grand Slam of the season underscored the bleak landscape of men's tennis in America.
Andy Roddick's 2003 US Open triumph marks the last time an American man hoisted a Grand Slam trophy.
For a nation that has produced 51 men's major winners in the Open era -- more than twice as many as any other country -- it's a baffling lack of success.
The burden to turn things around has long fallen on Isner as the top-ranked American, but after his first-round win over young compatriot Marcos Giron on Tuesday Isner said he couldn't afford to think that way.
"I don't look at it that way," he said. "I try not to focus on some of the negative things that people say about American tennis.
"I know I get the brunt of it a lot, because if I win and play well it's because I have a big serve and I can hit my forehand pretty well and that's it.
"But if I lose, it's only because that's all I can do. So, I mean, sometimes I feel like I can't win no matter what."
A lackluster French Open showing, with no American men in the quarter-finals, was followed by a dismal Wimbledon campaign that saw ninth-seeded Isner, the last US man standing, knocked out in the third round.
Although the game remains a niche sport in a country where football, basketball and baseball dominate, the lack of success is more keenly felt during the US Open, where the likes of Jimmy Connors, John McEnroe, Pete Sampras and Andre Agassi once ruled.
Isner seemed worn down when asked to comment on whys and wherefores of the depressing state of affairs.
"It's not the greatest it's been," he acknowledged. "But really I just, I don't know."