Every time Rafael Nadal has taken a step forward in 2015, he seems to follow it up with a step backward.

After winning his first tournament on grass in nearly five years when he captured the Mercedes Cup last week in Stuttgart, Germany, Nadal headed off to the Aegon Championship at the Queen's Club in London.

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Where he promptly lost in the first round to Alexandr Dolgopolov 6-3, 6-7, 6-4 to eliminate him and send home early in his second Wimbledon-prep tournament.

"I fought until the end," Nadal said, according to The Guardian. "He played well and he was a little bit better than me but I cannot say I am very sad the way that I played. [There is] nothing very negative, [after] winning a tournament last week.

"This week I lost an opportunity but my feeling, my thoughts, are no different today than yesterday. I am playing better than before and enjoying my tennis more on court than before. I will keep going, keep practicing hard. I hope to be ready to play well at Wimbledon."

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Nadal has dropped to No. 10 in the world rankings after losing at the French Open for the first time in six years and just the second time in 72 matches. He won an event in Buenos Aires is February but has not been the dominant force that he was in 2013, when he last was ranked No. 1.

Nadal has been very candid about his struggles, explaining that his physical health issues at the end of 2014 sapped much of his time to prepare this season, which in turn caused an unusual loss of confidence that he has been fighting himself to recover.

If Nadal has improvement, it has been incremental. Dolgopolov, Nadal's conqueror in London, bowed out in the second round of the Aegon Championship, losing in straight sets to Guillermo Garcia-Lopez 6-3, 7-6 (4).

As he continues to battle to return to his place among tennis' elite, the questions grow as to whether Nadal can ever recapture the form that pushed him to win 14 Grand Slam events.