The end came all at once for Rafael Nadal, and then it happened slowly.

Down one set and on the ropes against Mackenzie McDonald in the second round of the Australian Open on Wednesday, Nadal injured his hip while chasing down a shot in the eighth game of the second set.

His eyes, filled with concern, immediately turned to his coaches seated courtside at Rod Laver Arena. He then crouched in the corner to catch his breath. Moments later, he returned to continue, because for Nadal, the one thing worse than losing is quitting.

Knowing his day and his tournament were all but done, he watched two aces blaze by, bringing him to the brink of going down two-sets-to-love against McDonald, a 27-yearold American who has never cracked the top 40 in the world rankings. McDonald had played the match of his life for nearly two sets, then did what he needed to do to close out a 6-4, 6-4, 7-5 win over an ailing Nadal, who hobbled around the court for nearly another hour like a wounded deer.

Nadal’s injury came after McDonald had spent more than 90 minutes pasting the lines with his shots when he needed to most. Nadal, the No. 1 seed, called for a trainer, left the court to receive medical treatment for what appeared to be an injury to his midsection, near his right hip, then returned and played on.

The 36-year-old Nadal struggled to move and chase after balls with the abandon that has always been the hallmark of his game. He could barely generate power from his backhand. He somehow stayed even with McDonald through the first 10 games of the second set, hobbling around, taking wild cuts to try to end points quickly. But McDonald put just enough shots out of Nadal’s reach to break his serve in the 11th, then clinched the match when Nadal netted one last backhand return.

When it was over, Nadal left to a rousing ovation, taking an extra few moments to turn and wave to the crowd.

In a news conference 45 minutes later, the defending Australian Open champion said his disappointment was unimaginable, his voice cracking slightly as he spoke about suffering yet another injury in a career, despite all of its success, that has been filled with them.

The loss was the latest in a string of defeats that have plagued him recently as he has battled injuries and a wounded psyche. He also has had to adjust to fatherhood after the birth of his first child, a son, in October.

“He’s an incredible champion,” McDonald said of Nadal after the match. “He’s never going to give up.”

Nadal will likely take a break to get healthy again, then, if he can, turn his focus to the spring clay-court season and the French Open. It is a tournament he has won 14 times, and he calls it the most special of his career.

“I like playing tennis,” he said. “I know it’s not forever. I like to feel myself competitive.”

All that success will mean nothing, though, if Nadal can’t maintain his health.

Ultimately, that may be the one opponent that proves too tough, even for Nadal, but if there is any chance of delaying the inevitable a little longer, he will take it, regardless of the sacrifice.

“When you like do one thing,” he said. “Sacrifices always make sense.”