Rafael Nadal's Australian Open title defense lay in ruins on Wednesday after an injury-plagued defeat that shook up the men's draw, even as rain wreaked further scheduling havoc at Melbourne Park on day three.

A wincing Nadal suffered a left hip problem midway through his 6-4 6-4 7-5 loss to American Mackenzie McDonald at Rod Laver Arena and gloomily played out the match in pain.

The result not only opens up the top half of the draw, it also hands Novak Djokovic a boost as the Serb hunts a 10th title at Melbourne Park to draw level with Nadal's 22 major triumphs in the Grand Slam race.

"It has been like this a couple of days," said Nadal of his injury.

"I have a history of hip issues. I've had to do treatments in the past but it was not this amount of a problem."

"Sometimes it's frustrating. Sometimes it's difficult to accept. Sometimes you feel super tired about all this stuff in terms of injuries. Can't come here and say, lying, that the life is fantastic and staying positive and keep fighting. Not now. Tomorrow starts another day," Nadal said. "Now it's a tough moment. It's a tough day, and you need to accept that, and keep going.

"In the end, I can't complain about my life at all. So just in terms of sports and in terms of injuries and tough moments, I mean, that's another one. Just can't say that I am not destroyed mentally at this time, because I will be lying," Nadal added., reported the atptour.com. 

"Yeah, it's hard for me. But let's see. I mean, hopefully it's nothing too bad. In the end [it] has been three positive weeks in terms of practice. So I really hope that [this] doesn't put me out of the court for a long time, because then it's tough to make all the recovery again. It's not only the recovery. It's all the amount of work that you need to put together to come back at a decent level."

"I didn't want to retire, to be defending champion here. I didn't want to leave the court with a retirement. Better like this at the end. I lost. Nothing to say. Congratulate the opponent," Nadal said. "That's the sport at the same time. Just try your best till the end. Doesn't matter the chances that you have. That's the philosophy of the sport. That's the essence of the sport by itself. I tried to follow that during all my tennis career, and I tried of course to not increase the damage, because I didn't know what's going on."

(With input from Reuters)