Men's Tennis: Sam Querrey Among Those Looking to Pull a "Del Potro" in '12

Probably the most remarkable comeback story in tennis this year was the one by the young Argentine Juan Martin del Potro. The 2009 U.S. Open champion started the season ranked outside the top 250, but currently stands at 15 after winning two titles this year.

The finalists at last week's Challenger tournament in Sacramento, Calif.—Sam Querrey and Ivo Karlovic—are both in the process of working themselves back up the rankings after injury. Here's a look at the players looking to emulate del Potro, whose return from a career-threatening wrist problem can be considered a success up to this point.

Sam Querrey

Things couldn't have gone much better for Querrey in 2010. He won four titles under as many conditions—on grass, hard (indoors and out) and red clay. That red clay title marked the first time an American man had won on the dirt in Europe since 2003.

He stayed in the top 25 for a good portion of '10, but lost momentum after the U.S. Open that year, which carried over into the first half of 2011. An elbow injury that required surgery didn't help matters, but in recent weeks, Querrey has found some success on the Challenger circuit and is back to winning matches.

Ivo Karlovic

The Croatian serving machine has proven that his game has a lot of versatility, with titles on clay, grass and hard courts. It turns out his Achilles' heel actually turned out to be his Achilles' heel, which led to a plummet down the rankings. However, in the past few months, Karlovic has worked his way well back into the top 100, thanks to a recent run of success at the Challenger level.

He beat Querrey in the finals in Sacramento. Is a return to the top 25 within the big man's reach?

James Blake

The former world number four did not enter 2011 with many people optimistic about his future, as a knee injury slowed him down in 2010, when he finished the year outside of the top 100 for the first time since 2000. Blake dug deep, and thanks to two Challenger wins and decent results on the main tour, has gotten himself back in the top 70. His forehand is still explosive and can lift him higher up the rankings in '12.

Robby Ginepri

Who would've thought a squirrel could knock a player so far down the rankings? That's what happened to Robby Ginepri in the well-documented incident of him wrecking on his bike to avoid one on a trail, leading to him picking up a pretty severe injury. After missing most of the season, Ginepri started working his way back toward the latter half of '11. A threat on hard and clay courts, Ginepri will have few points to defend and could get a rankings boost with some solid wins.

Tommy Robredo

Though he's still in the top 50, the former top 10 player has been plagued by injury for most of the '11 campaign. That's tough, because the start of the season couldn't have gone better. The Spanish veteran ran off a 16-5 record before suffering an abdominal injury that's affected him throughout the rest of the season. Provided his health improves, at least a top 20 return is possible.