Mackenzie McDonald produced one of the upsets of the Australian Open on Wednesday as he eliminated defending champion Rafael Nadal 6-4 6-4 7-5 in the second round, with the Spaniard hampered by an apparent leg injury.

There were ominous signs early on as number one seed Nadal had his serve broken in the opening game of the match, and McDonald secured a second break en route to wrapping up the first set.

It was more of the same in the second as McDonald took advantage of some uncharacteristically sloppy play from the 36-year-old, before Nadal seemed to hurt himself.

At 4-3 down in the second set, Nadal pulled up with an apparent upper leg issue after chasing a forehand, and his movement was clearly hampered from that point on.

In typical defiant fashion, Nadal's level rose in the third, hitting 24 winners, but as he improved, so did McDonald, who did not allow Nadal a single break point opportunity.

The 22-time grand slam champion saved break point at 4-4 to hold serve as he tried to get back into the contest, but was unable to repeat the trick in his next service game as McDonald secured the break before serving out to clinch a famous win.

It is the latest in a troubling run of form for Nadal, who received multiple injury timeouts on his way to a seventh loss from his last 10 matches dating back to the US Open.

McDonald will play the winner of Yoshihito Nishioka and Dalibor Svrcina in the third round.

Data Slam: Nadal joins dubious company as top-seed casualty

Nadal is the first top seed to be eliminated from the Australian Open in the second round since Gustavo Kuerten in 2001.

The Brazilian was also a clay specialist, winning all three of his grand slams at the French Open.

ACES/DOUBLE FAULTS

Nadal – 6/2

McDonald – 14/2

WINNERS/UNFORCED ERRORS

Nadal – 42/31

McDonald – 42/22

BREAK POINTS WON

Nadal – 2/4

McDonald – 5/8