Though there's been great parity in recent women's Grand Slam tournaments, with seven winners in the last seven Slams, the men's side has been completely dominated by the Big Three of Roger Federer, Rafael Nadal and Novak Djokovic.
This year's U.S. Open is the first Grand Slam event in a while that offers a real opportunity for a sleeper to win in both the men's and women's tournaments.
On the men's side, Nadal's withdrawal from the tournament due to injury leaves one less Goliath to defeat. Though Federer is in the midst of a late-career resurgence, it's been four years since he's won at Flushing Meadows, and Andy Murray showed at the Olympics that Federer is not invincible.
Any sleeper on the gentleman's side will still have to top defending champion Djokovic, but he does not yet have quite the aura of invincibility that surrounds Federer and Nadal.
On the women's side, Serena Williams's recent return to dominance has left many of her opponents nervous, but the U.S. Open is the venue that rattles Williams the most. She has had emotional outbursts at the last two Opens she played in, and she told the New York Times, according to Paul Newman, that she thinks something will likely go wrong again at this year's Open.
While Williams' total of three singles titles at the U.S. Open is an amazing feat, she's only won the major once in the past decade.
These factors are just enough to give Williams' opponents hope that they can defeat her at Flushing Meadows and continue the era of parity in the women's game.
Here is a look at five sleepers, two on the men's side and three on the women's side, who have what it takes to surprise the tennis world with deep runs at this year's U.S. Open.