Djokovic won a record-extending 10th Australian Open title last month to draw level with his great rival Rafa Nadal (36) on 22 Grand Slam victories and leapfrog Carlos Alcaraz (19) into the top spot in the ATP rankings.
He already holds the record for the most weeks as the men's number one after surpassing Roger Federer's mark of 310 weeks in March 2021 and began his 377th week at the top on Monday to go level with 22-times major champion Graf.
Russian world number five Andrey Rublev (25) said Djokovic had shown that anything is possible.
"And at the age of 35, he still can be the best player in the world and break records," Rublev, who lost to Djokovic in the Australian Open quarter-finals, told reporters in Doha.
"If you do the things right, you can perform at the highest level ... age doesn't matter. That's what it means to me."
Former world number two Alexander Zverev (25) said Djokovic had shown how consistent he can be by dominating his rivals in the last decade.
However, Zverev said that watching Graf being overtaken would be bittersweet for him.
"He's surpassing Steffi, so as a German, obviously I always loved her having that record. But credit to Novak, I think that shows how great he is," Zverev said.
"I'm sure that he's going to break a few more records. I'm not sure there are many left, but the ones that are left, maybe he will."
Djokovic returns to action in Dubai later this month.
