It was a simple letter that brought Adam Silver from legal affairs to the eventual leadership of one of the most successful sports empires.

Silver, a litigation associate at New York law firm Cravath, Swaine & Moore, wrote a letter to NBA commissioner David Stern in early 1992 for advice. He soon received an invitation to meet the NBA boss, who had also been a lawyer, in Stern's office.

"I remember I was so nervous that the room felt even hotter than this room today," recalls Silver on a recent warm afternoon in Shanghai. "I put my hands on the table and I was nervous that he might see how much I was sweating. I was pretty intimidated meeting him."

That meeting turned out to be the genesis of a symbiotic relationship that has lasted for more than 20 years after Stern offered Silver a job as his special assistant.

Silver frequently appears at Stern's side and is involved in every aspect of business operations at a time of great expansion for the NBA. Stern's trust in Silver became evident when former NBA deputy commissioner Russ Granik retired in 2006. Stern tapped Silver to step into the role, and last year announced Silver would take over as commissioner.

The US media describes Silver as a great departure from Stern. Whereas Stern can be argumentative and aggressive, Silver seems dispassionate and more calm.

Silver, talking of his first impressions of Stern, says: "He was very direct, very smart and very thoughtful,"

Self-proclaimed as a collaborative, hard-working and loyal man, Silver played a pivotal role in helping the two sides reach agreement when Stern and union leader Billy Hunter could not come to terms during labor negotiations in 2011.

Jeffrey Kessler, a lawyer for the NBA Players Association, says in a Wall Street Journal story that ran last October: "Silver is a much calmer presence than David".

Living in an apartment near the NBA's head office on Fifth Avenue in New York, Silver is famous for working long hours, just as the energetic Stern still does.

"I am fortunate that I have a job that blends into my personal time as well," he says. "The NBA is very much a family environment - we all tend to work and socialize together. Some of my best friends are my colleagues."

His dedication has meant less time for a personal life. "Hopefully not forever, but I am still single," says Silver, who has four siblings.

Growing up north of New York in wealthy Westchester County, Silver is a Knicks fan and enjoys running, tennis and golf. "He is a very good athlete," says Heidi Ueberroth, president of NBA International. "Every time we have events like bowling or tennis, he is always good."