No. 1 seed and defending champion Rafael Nadal was shocked Wednesday in the second round of the 2023 Australian Open, falling 6-4, 6-4, 7-5, to American Mackenzie McDonald.

While Nadal was outplayed in the first two sets, the deathblow to his chances of repeating as champion came in the third set, when he suffered a hip injury and needed to be checked on by a doctor.

Nadal finished the match, but he was clearly limited by the ailment. He explained afterward that he didn't want to retire due to his status as the reigning champ:

Watching Nadal struggle to the finish line was difficult for some of his fans, and they responded in kind on social media:

Others focused on Nadal's lingering goodbye to the supportive fans at Rod Laver Arena and expressed hope that Wednesday's loss was not his Australian Open swansong:

Nadal's loss is a major story given his status as an all-time great and winner of a record 22 Grand Slam singles titles, but McDonald's performance deserves praise as well.

The 27-year-old entered the 2023 Australian Open having never made it further than the fourth round at a Grand Slam, including four exits in the second round or earlier out of his five previous Aussie Open appearances.

McDonald has also never won an ATP singles title, with his closest call being a three-set loss to Jannik Sinner in the Washington Open final in 2021.

Wednesday's victory over Nadal was by far the biggest of McDonald's career, and while the injury helped his cause in the end, the American already had the Spaniard on the ropes entering the third set.

Nadal has overcome many of those types of deficits over the years, so it is possible he may have done it again had he been healthy, but McDonald sealed the deal in a situation where many have tended to fold.

Now, McDonald is set to face 31st-seeded Yoshihito Nishioka of Japan in the third round and could face No. 16 seed and fellow American Frances Tiafoe in the fourth round.

As for Nadal, he will regroup and tend to his injury in hopes that he will be fully healthy by the end of May, when he will look to win a 15th career French Open title.