The only former champion left in the men's draw at Melbourne Park, Nadal is tied on 20 majors with Roger Federer and world number one Novak Djokovic, who are both absent from the tournament, Reuters reported.
A second Australian Open title will also make the Spaniard only the second man after Djokovic to win each of the four Grand Slam titles twice since the sport became professional in 1968.
Nadal has, however, repeatedly said that his only objective at this year's opening major was to stay healthy, having returned to the Tour after recovering from a long-standing foot problem and contracting COVID-19 last month.
"I said here before the tournament start, things are not going to be perfect, but every day that I'm going to spend on court, the chances to play better are higher," said Nadal, who won an Australian Open tune-up event, his first since August.
"I think I am doing things well. I'm excited about the fact that I'm going to be playing in a third round for one more time here after all the things I am going through. I don't have big pressure on my shoulders, honestly. I don't feel it."
The 2009 champion's only previous meeting with the 126th-ranked Hanfmann came on the Roland Garros clay in 2019 when Nadal lost just six games en route to a straight-sets victory.
The sixth seed needed five match points before sealing victory when Hanfmann sent a forehand long.
Nadal said he wanted to be more aggressive on court.
"Only five matches after such a long period of time, not enough in general terms to appreciate if I am able to change something or not," he said.
"If I'm able to play more matches in the next couple of months, I hope to be able to play better and better and to improve couple of things."
‘Living like a hermit’
Women’s world number one Ashleigh Barty said continuing to live like a "hermit" is helping her breeze through the Australian Open draw.
Australian Barty, 25, reached the third round by beating Italian qualifier Lucia Bronzetti 6-1 6-1 on Wednesday.
As she aims to become the first home champion since 1978, Barty says trying to avoid coronavirus as rates rise in Melbourne has not affected her.
"For us, it's pretty low-key anyway," she said.
"We come and practice and do what we need to do. Otherwise a good book and a coffee and I'm set."
The two-time Grand Slam champion has not dropped a game on her serve at Melbourne Park this week, beating Bronzetti in 52 minutes to back up another emphatic win in the first round.
Barty has started the 2022 season by winning all six of her matches, having lifted the Adelaide International title last week.
On the strength of her service game, she said: "I'm continually trying to make it a weapon.
"I'm not the biggest girl out there, but I know I've got a sound technique and I know if I can get my rhythm right and use it effectively, it can be a weapon.
"As a kid, I was always serving baskets and baskets of serves to try to create that weapon, try to create a really sound shot."