Rafael Nadal could miss 6-8 weeks with hip flexor injury

Rafael Nadal upset in 2nd round of the Australian Open (1:34)

Defending champion and No. 1 seed Rafael Nadal loses to American Mackenzie McDonald in the second round. (1:34)

MELBOURNE, Australia -- World No. 2 Rafael Nadal could miss up to six to eight weeks after an MRI revealed he sustained a grade 2 left hip flexor injury in his second-round loss to American Mackenzie McDonald at the Australian Open, it was announced Thursday.

The diagnosis means Nadal will almost certainly miss the ATP 500 tournaments in Dubai and Acapulco. He will be in a race to be fit for Indian Wells and Miami in early March.

Nadal, who was the defending champion in Melbourne, lost to McDonald in straight sets on Wednesday and pulled up lame reaching for a ball late in the second set. Nadal sought treatment off the court before the third set but was unable to regain ascendency in the match, losing 6-4, 6-4, 7-5.

The iliopsoas muscle group is a deep group within the hips which connects the spine to the lower limbs, and in an effort to regain fitness, Nadal will return to Spain to receive treatment and physiotherapy.

Nadal sustained a similar injury at the 2018 Australian Open, when he lost to Marin Cilic in the quarterfinals. In his news conference following the loss to McDonald, Nadal said he would do everything in his power to come back fit, but admitted his recent run with injury was "frustrating."

"Sometimes it's difficult to accept," he said. "Sometimes you feel super tired about all this stuff in terms of injuries."