The second week at a major tournament is when an underdog's dream usually dies.
Momentum and confidence are huge factors in tennis, but when a player ranked outside the top 100 runs up against a former U.S. Open champion like Novak Djokovic or another past champion and multiple-time Grand Slam winner like Rafael Nadal, you can throw those two factors out the window.
Still, one of the best things about Grand Slam tennis is the fact that unknowns can become household names in just a few days.
Below we'll examine three of the biggest overachievers still alive in the 2013 U.S. Open singles draws heading into the first weekend at Flushing Meadows.
Not many tennis fans knew who Daniel Evans was before he upset No. 11 Kei Nishikori in the opening round of the men's singles draw on Monday.
Evans took out the former Australian Open quarterfinalist in dominant fashion, winning in straight sets to reach the second round despite making just his first career appearance in the U.S. Open main draw.
The 179th-ranked men's singles player in the world is still alive heading into the third round, though, after he knocked off Aussie Bernard Tomic in four sets in the second round. Evans looked completely over-matched in the opening set, losing 1-6, but fought back to level the match before breaking Tomic's will in a third-set tiebreaker.
He would cruise in the fourth set to secure a winnable matchup with No. 19 Tommy Robredo.
If Evans keeps playing quality tennis and keeps winning, he could potentially face No. 7 Roger Federer (round of 16) and No. 2 Rafael Nadal (quarterfinals).
While many American tennis fans have had their eyes on the upcoming round-of-16 clash between Serena Williams and Sloane Stephens, few are aware of Alison Riske, and the fact that she's just one win away from reaching the round of 16.
The current world No. 81, who typically plays her best tennis on grass as pointed out by SI's Beyond the Baseline on Twitter, will take on seventh seed Petra Kvitova in the third round this weekend after defeating Tsvetana Pironkova in Round 1 and 28th seed German Mona Barthel in Round 2:
Riske has yet to drop a set heading into her third-round matchup and has already ensured her best career finish at the U.S. Open, win or lose. In her only other appearance in the main draw at the season's final Slam two years ago, Riske lost in the opening round.
The 23-year-old is one of just four American women remaining in the singles draw coming into the weekend.
Another overachieving American to watch for this weekend is 25-year-old Tim Smyczek, who has taken advantage of a favorable draw to reach the third round at a major for the first time in his career.
The 109th-ranked player in men's singles beat James Duckworth in the opening round and then survived Alex Bogomolov Jr. in a hard-fought five-set match to set up a very winnable third-round showdown with unseeded Spaniard Marcel Granollers, per former professional tennis player Nick Lester on Twitter:
If Smyczek can win that match, he'll be into the round of 16 where he would likely get a shot at world No. 1 Novak Djokovic.
Either way, this is only Smyczek's third career appearance in the U.S. Open main draw, and he's clearly trending up at Flushing Meadows. He lost in the first round in his first appearance in 2010 and fell in the second round a year ago.
Follow Bleacher Report Featured Columnist Patrick Clarke on Twitter.
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