Recently in a interview with German publication, he mentions an interesting story about getting a mailed package from Muhammad Ali.
We get more from Spurs Nation:
Nowitzki told the German publication Spiegel Online International that shortly after the Dallas Mavericks’ upset Finals series victory over Miami, he received a package from Ali that included a boxing glove with the inscription “You are the greatest.”
“Please don’t ask me immediately about the political meaning of the gift,” Nowitzki told Spiegel. “I was simply happy and sent Ali a golden basketball with a similar inscription.”
Classy move from both of the greatest of all-time to play their respective sports.