Isner, Sock and Querrey lead U.S. men in Melbourne

An American man has not won a Grand Slam since the 2003 US Open. The debate for years has been simple—who will be next? It is unclear if any American will have a chance to truly challenge for the title in Melbourne, but there are plenty who could threaten to make the second week.

1

Age: 31

Ranking: No. 19

Best Australian Open result: 2010 and 2016, round of 16

Isner had a great chance to make his first quarterfinal run at the Australian Open last year, overcoming Feliciano Lopez to set up a fourth round clash with David Ferrer. Isner would beat the gritty Spaniard in their only other match last year, but Ferrer came away with the win in Melbourne in straight sets.

There is not a player in the world who wants to play Isner on a hard court. The University of Georgia alumnus possesses arguably the greatest weapon in tennis, his serve. It doesn’t matter if he’s playing Andy Murray (who's in his section of the draw) or anyone else—if Isner has a good serving day, he will be able to hang around with any opponent he plays.

2

Age: 24

Ranking: No. 23

Best Australian Open result: 2014 and 2016, second round

Sock has yet to find success at the Grand Slam level, but he's made it one of his main goals for 2017. Last year, the Nebraskan had to overcome a tough five setter in the opening round against another player on this list, Taylor Fritz, before running out of gas against Lukas Rosol in the next round.

But this may be the breakout major for the powerful 24-year-old. Perhaps beating former US Open champion Marin Cilic in Flushing Meadows last year will give Sock the confidence he needs (he's cast in the same section of the draw as Cilic again). Sock may not be ready to win in Melbourne, but do not count him out from making a deep run.

3

Age: 29

Ranking: No. 31

Best Australian Open result: 2007, 2008, 2013 and 2014, third round

Querrey’s Australian Open campaign in 2016 got off to a fast start, but the heat got to him after winning the first two sets in his opener against Dusan Lajovic, forcing him to retire before the fifth set. Still, the year would end up being a resurgent one for Querrey. Not only did he stun then-No. 1 Novak Djokovic at Wimbledon, but the Californian also won his first title since 2012 in Delray Beach.

If you beat Djokovic at a major, it is safe to say that you can never quite be counted out of a match before it starts. Querrey has a deadly serve-and-forehand combo, but the key for him in Melbourne will be his confidence. Querrey played great tennis for most of 2016, but has lost his last six matches. If anyone is able to pull off another shocker in the third round if he faces top-seeded Murray, it's Querrey.

4

Age: 27

Ranking: No. 33

Best Australian Open result: 2015 and 2016, third round

Johnson’s game is not much different from his compatriots in that his strengths are his forehand and serve. One of the best players in college tennis history, the University of Southern California alumnus distinguishes himself in another area—his competitiveness.

Johnson got a tough draw in Flushing Meadows, losing to Juan Martin del Potro in the second round, but had a strong summer before that. He pushed Murray to a third-set tiebreaker in the Rio quarterfinals after reaching the round of 16 at Wimbledon. Don’t be dissuaded by Johnson’s routine loss to Grigor Dimitrov in his first match of 2017—the Bulgarian is a dark horse in any draw (he won the title). He just missed the seeding cutoff, so he's got another tough draw, nestled right near fourth seed Stan Wawrinka.

5

Age: 19

Ranking: No. 91

Best Australian Open result: 2016, first round

Fritz is not the fifth-ranked American, but he may very well be the most talented teenager the country has seen since Andy Roddick (the nation's last Grand Slam champion). Last season, Fritz reached his first ATP final in Memphis and took a set off of 17-time Grand Slam champion Roger Federer on grass in Stuttgart.

The 2015 US Open junior champion peaked as high as No. 53, but has since fallen outside the Top 90, struggling toward the end of the season.

“I have to be proud of being where I'm at at the age I'm at,” Fritz said after losing to Sock in five sets in the US Open first round. “It's tough because I just set the expectations so high for myself. I want to do better and I want to do more than I've done.”

Fritz has been dealt a tough draw in Melbourne, facing Gilles Simon in the first round and possibly an on-fire Milos Raonic in the second.

Lastly, don't forget about Ryan Harrison, who is currently ranked No. 89. While his ranking seems low, Harrison is playing better tennis than he has in years, reaching the third round at the US Open last year.