Japanese lucky loser Taro Daniel takes Nadal's place and faces Jo-Wilfried Tsonga in the second round.
Nadal endured an injury-plagued 2018 season that saw him contest only nine tournaments due to hip, knee, abdomen and ankle injuries and the world number two said the decision to skip the season-opener was precautionary.
"So I don't play here and I probably secure that I'm going to be 100 per cent for Melbourne".
"When you increase the intensity on the muscle when competing, then there is a big risk to make it something bigger".
Nadal finished the year with a 45-4 win-loss record and five titles, ending up second to Novak Djokovic in the rankings.
On Wednesday, the Spaniard confirmed he was pulling out of the ATP 250 event in Brisbane due to a small strain in his left thigh. "He is one of the greatest legends of all time and we want to see him play".
He further added "for me it's a big goal to be ready for there [Australian Open] and I'm going to fight for it".
Nadal was limited to nine tournaments past year due to a string of ailments and his preparation for the Australian summer was disrupted by ankle surgery in November.
"And was awful news for me that things were not the way that I planned, but coming back from a period of time outside of the competition and coming back from surgery, you know, there's always a chance that this kind of stuff happens".