Rafael Nadal faces up to eight weeks out of action with the hip flexor injury he sustained on his way out of the Australian Open.

The defending champion and top seed in Melbourne was bundled out 6-4 6-4 7-5 by world number 65 Mackenzie McDonald on Wednesday, struggling to move around the court during the closing stages of the contest.

He refused to retire and afterwards confirmed he aggravated an issue he had been suffering with for a couple of days. The 36-year-old Spaniard knew the problem he had been suffering with for a "couple of days" had worsened, but he was unsure exactly what was causing it.

Now Nadal has clarity, receiving details of the injury after tests on Thursday.

He knows that provided all goes to plan, he should be back on court for the clay-court stretch in Europe leading up to the French Open, where the 14-time winner is also the defending champion.

Nadal wrote on Twitter: "Good afternoon. I have carried out medical tests after the defeat yesterday. The MRI shows a grade two lesion in the iliopsoas of the left leg. Now it's sports rest and anti-inflammatory physiotherapy. Normal recovery time six to eight weeks."

Buenas tardes. He realizado pruebas médicas tras la derrota en el día de ayer. La resonancia magnética muestra una lesión grado 2 en el Psoas Iliaco de su pierna izquierda. Ahora toca reposo deportivo y fisioterapia anti inflamatoria. Tiempo normal de recuperación 6 a 8 semanas. pic.twitter.com/xwcKSyTzhp
— Rafa Nadal (@RafaelNadal) January 19, 2023

The 22-time major winner may struggle to get back to full fitness in time for the Indian Wells and Miami Masters 1000 events in March.

Those are due to be preceded on his schedule by a high-profile exhibition match in Las Vegas against Carlos Alcaraz on March 5; however, both men are presently injured, raising doubts over whether that will go ahead.

Nadal was distraught to suffer yet another injury setback, after severe foot and abdomen problems hit his 2022 season.

"In terms of sports and in terms of injuries and tough moments, I mean, that's another one," Nadal said on Wednesday. "I can't say that I am not destroyed mentally at this time, because I will be lying."