By Chris Oddo                           Photo Credit: Tony Chang

Now that he's back in the top ten, people want to know: when will Juan Martin del Potro start beating the top ten again?

The 2009 US Open champion has come a long way from his career-threatening wrist surgery, which took him off the court for nearly all of 2010. But now that he's got a solid year-plus of post-surgery competition under his belt, the next hurdle is still beckoning.

With only three wins in fourteen matches versus top ten competition since his post-surgery return, Del Potro has yet to prove that he's a worthy candidate to be included in all that "who can crack the big four?" talk that incessantly swirls among the tennis cognoscenti. (It’s not really an insult though, because nobody has.)

That said, there is no denying Del Potro's capabilities. His game is electric, his quickness for a man his size practically unheard of and his commitment to maintaining a slow and steady march up the rankings has been unyielding.

And he's been frustratingly close at times, too. While getting the rust off and pushing his rankings all the way back from a 2011 low of No. 485, the tall Argentine has had to deal with some very difficult draws, particularly in the Grand Slams.

He faced the hottest player in the world at Roland Garros in the third round, managing to take a set off Novak Djokovic when other players were happy just to get games. He ran into Rafael Nadal at Wimbledon in the fourth round, and played exceptionally well, pushing the third set to a tiebreaker before losing in four. He also notched two titles last year, in Delray Beach and Estoril.

But as good as he's played -- and as good as we know he can play -- the fact remains: Delpo is not measuring up to the game's elite players at this stage of his comeback.

Can he? Well, we all know the answer to that. Maybe a better question is, when will he?

Aside from two wins against Robin Soderling in the first half of 2011, Del Potro's only other top ten win came when Novak Djokovic had to retire from Davis Cup play in Argentina's semifinal against Serbia.

In his other eleven unsuccessful attempts, Del Potro has had his moments, but never the moment.

There have been times where he's inspired hope in all of us that he'd one day return to his 2009 form, where he'd unleash mighty forehands and serves that were flat-out devastating. But he's also had moments where his level has dropped. Where it was clear that he's not yet all the way back yet.

These are the moments where his other top ten foes expose him for what he is at the moment: a player who is almost all the way back, but not quite yet.

Tomorrow, after reaching the semis in Rotterdam, Del Potro will get another chance to knock off an elite talent when he faces red-hot world No. 7 Tomas Berdych.

Whether he wins or not, one thing is clear: These are the matches that Del Potro needs to start winning if he wants to keep moving higher.