The North American hard-court season will conclude with a bang this summer in Flushing Meadows, N.Y., site of the 2013 U.S. Open.
Andy Murray and Serena Williams return as defending champions on the men's and women's side, respectively, but each will have to fend off a loaded field of contenders in order to retain the crown.
What's more, there are a handful of notable dark-horse challengers taking part who will make their task of repeating that much more difficult.
Here we'll highlight a trio of dark horses to watch for at the U.S. Open this summer.
Of the four Grand Slam tournaments, the U.S. Open has been where John Isner plays his best tennis.
The top-ranked American reached the quarterfinals in New York in 2011 (his best-ever finish at a major) and has reached the third round in each of his past four trips to the Big Apple.
On top of Isner's encouraging past at this event is the fact that the 6'10" star has been playing lights-out on the hard courts of North America this summer. He won the Atlanta Open at the end of July before reaching the final of the Citi Open in Washington, D.C., earlier this month. And most recently he made a run to the final of the Cincinnati Masters last weekend, where he lost to Rafael Nadal.
Isner is 13-3 overall on the hard courts this summer coming into the year's final Slam, and that bodes extremely well for his chances of making another memorable run in the men's draw.
British teenager Laura Robson knocked off three-time U.S. Open champion Kim Clijsters and former French Open champion Li Na en route to reaching the fourth round at Flushing Meadows a year ago. In 2013, the world No. 32 will look to build upon those results.
Robson made major strides at the Australian Open and Wimbledon earlier this year, reaching the third and fourth round, respectively. Both were career-best finishes and have her on pace for another impressive run in New York.
The left-handed up-and-comer has only played one hard-court tournament since Wimbledon, falling in the second round in Carlsbad earlier this month. But expect her focus to be much improved at the U.S. Open.
While a slew of early upsets at the All England Club no doubt aided Jerzy Janowicz's brilliant run to the semifinals of Wimbledon earlier this summer, make no mistake: The 6'8" Pole can play with the elite in men's tennis.
Now all the way up to No. 15 in the ATP world rankings, Janowicz will enter just his second U.S. Open main draw with solid odds (40-1, according to bet365.com) to take home the title.
The 22-year-old's summer hard-court season has been nothing to write home about, but he's been experiencing breakthrough runs at Grand Slam tournaments as of late, and even pushed Rafael Nadal to the brink earlier this month at the Rogers Cup in Montreal.
Janowicz reached the third round at both the 2013 Australian Open and the 2013 French Open despite making just his first career main draw appearance at each event.
One of the fastest servers in the sport, Janowicz has the tools to spring an upset or two on his way to the later rounds this summer at Flushing Meadows.
Follow Bleacher Report Featured Columnist Patrick Clarke on Twitter.