Juan Martin del Potro says his backhand has gotten better, but it’s not good enough to win Grand Slam titles.

Four wrist surgeries have limited del Potro’s ability to fully engage his left wrist while driving his two-handed backhand.

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While del Potro has worked diligently to sharpen his one-handed slice backhand, the 2009 US Open champion believes his two-handed backhand must get stronger for him to win another major.

“I feel better with my backhand, but it's not good enough to win a title like this or to win the top guys in a row,” said del Potro after his US Open semifinal loss to world No. 1 Rafael Nadal. “Depends of their game, too, because against Rafa, you must hit winners from both sides. I didn't tonight. He played maybe 80 percent of the game to my backhand, and there is an advantage for him.”

The 28-year-old Argentine said if he doesn’t full regain the sting in his backhand he will make more tactical adjustments in future meetings against the 10-time Roland Garros champion.

“I don't know if, in the future, I can beat him again, but is just matter of time if I can get my old backhand one day or not,” del Potro said. “But I will try to change the games if I have the chance to play against him again.”

Even with his compromised backhand, del Potro's iron hammer forehand has now grown to legendary proportions.

Just ask Thor.