The Argentine was beaten 7-6, 7-6 in the quarter-finals of the Sydney International by wildcard Mikhail Kukushkin on Thursday.
In a chat with media after the loss, the former US Open champion confirmed that he is still struggling with his wrist, after an 11-minth layoff for wrist surgery, and feels that he is going to battle in Melbourne next week at the opening Grand Slam of the year.
"I served well, but my wrist hurts a little bit more than yesterday, and I couldn't hit harder than my last match," Del Potro said.
"He played very smart. He was all the time playing to my backhand and playing slices."
He added: "I will be waiting for a tough draw in Melbourne for sure.
"But I have to think about my opponent and my first match on tour again playing a Grand Slam. Many people will be watching me and expecting me to win some matches.
"It's not easy, but everybody has to know I'm 338th player in the world at the moment. I just beat the top 20 player here, top 50, it's great for these kind of players, so I'm happy for that.
"But I want to meet also Federer, Djokovic, these guys, because I miss them when I was at home. I only speak with WhatsApp or by phone. Now I will meet the biggest players of this sport again," he added.
Del Potro said he was not going to take his foot off the pedal when it came to training despite the discomfort with his wrist.
"I need to keep training, and training hard every day, I will have day off maybe tomorrow, I will fly to Melbourne tomorrow," Del Potro said.
"I don't have a magic solution, just be patient, stay calm, and do my best every day to do a big effort to come back.
"This is my biggest challenge on my new career again," he added.