Nadal has been out of action for months recovering from a wrist injury and then was hospitalised for appendicitis.
In his first official match of 2015, the World number three lost 1-6, 6-3, 6-4 against Berrer in Qatar and looked very rusty on court.
According to a report after the match in the Sydney Morning Herald, Nadal said that he wanted to play in the Australian Open but there were doubts.
"I also want to play in the Australian Open which is a tournament I like a lot. I don't know if that will be the case either, but I am going to work for it. If not I will be playing at Rio and Buenos Aires.
"The season is long. After coming back from injury you can't see the immediate moment, you have to look further ahead a little bit.
"Now in my mind I have to practise well and try to be ready for Australia, but I know it can happen that I will go there and lose. Perhaps I will win a couple of matches there, I don't know," he added.