Novak Djokovic apologised but confirmed he had been dealing with a blister after only playing a set of his exhibition match in Adelaide. (More Tennis News)
The world number one had reportedly withdrawn and was replaced by Filip Krajinovic for a clash against Jannik Sinner.
But Djokovic played the second set, winning it 6-3 after Krajinovic had taken the opener 6-3 on Friday.
The 17-time grand slam champion, who had a blister on his right hand, apologised after the match.
"I'm sorry that I didn't step in on the court from the beginning," Djokovic told Channel 9.
"I had to do some treatment with my physio and wasn't feeling my best the last couple of days, I didn't know how I'm going to react.
"I wanted to play and I wanted to get out here and hopefully it was enough for you guys to see all three of us performing in front of you on the court today, I hope you enjoyed."
Djokovic, who came out of hotel quarantine on Friday, said he could not pass up the opportunity to play in front of fans.
"It's not easy but it's part of what we do. We are professional athletes we learn over the years to play with the pain and it's just a question and case whether that pain is bearable or not," he said.
"Obviously coming off from the hard training block and having an ATP Cup and Australian Open around the corner you don't want to risk it too much.
"But the emotion was so strong in me to come out on the court today seeing almost full stands, I had to play, that's it, I had to play."
Djokovic is due to play the ATP Cup starting on Tuesday, before the Australian Open begins on February 8.