Robert Lewandowski's current contract runs until summer 2019 but as reported by rumours, he wants to stay a few seasons longer at the Bundesliga club.
The 28-year-old netted this season so far ten times in thirteen appearances.
Rummenigge said about the negotiations: "Things are looking good.
"Talks have been ongoing for a number of days and we have gotten off to a good start. And what goes on for a while usually results in something good...
"When we reach an agreement with Lewandowski, we will announce it the day after. We will not be making a spectacle out of it," he said.