"Hi everyone. Unfortunately, the injury I suffered in Acapulco before starting the tournament is in the same area as the one suffered in Melbourne".
Nadal's withdrawal from Indian Wells and the Miami Open comes a day after Stan Wawrinka pulled out of both tournaments.
On Wednesday, Nadal announced that the same injury forced him to withdraw from the ongoing Mexican Open in Acapulco, leaving his status uncertain for a USA swing that included the BNP Paribas Open and the Miami Open.More news: Russia's super weapons 'not the start of arms race', Kremlin says
He added, "The spot is really similar to Australia, so I need to be sure about what's going on the next couple of days, and then we're going to work hard to try to recover as soon as possible".
As confirmed now, Nadal took the right decision to opt out of ATP Acapulco.
Nadal, who lost his number one ranking to Roger Federer last month, has pulled out of or retired from eight tournaments in a row.
Rafael Nadal has been forced to withdraw from the Masters Series events in Indian Wells and Miami.More news: Theresa May sets out 'hard facts' on Brexit in speech
The 32-year-old, who has suffered defeats to lowly-ranked Mirza Basic and Tallon Griekspoor, has now made a decision to step away from the tour again and hopes to be fully fit for the clay season.
Wawrinka is one of the strongest players on clay and reached the final of the French Open a year ago after winning the title in 2015.
An 11th title at Roland Garros will be his primary goal, and that could see the 16-time Grand Slam champion play it very carefully in the build-up.
Nadal's decision could suggest he is prioritising a return in time for the clay court season which begins at the Monte Carlo Masters in April.More news: Rutgers makes right on home court advantage in Big Ten Tournament