Director John G. Avildsen died Friday at the age of 81 at Cedars-Sinai Medical Center in Los Angeles, according to his eldest son, Anthony Avildsen.
"He was a pretty extraordinary man in my estimation. He was super talented and very driven and very stubborn, and that was to his detriment but also often to his benefit," Avildsen told The Associated Press.
John G. Avildsen won the 1976 Academy Award for best picture with "Rocky," which starred a young Sylvester Stallone in the title role as an underdog boxer. It was nominated for seven other Oscars.
The film was shot with a budget of less than $1 million (about $4.5 million, or 4 million euros today) and was completed in 28 days.
"The first time I showed it to 40 or 50 friends, they all freaked out, so that was encouraging," he once recalled. "But I guess when I saw the lines around the block, it began to take on a reality."
'He changed my life'
Stallone praised the director Friday night for believing in him.
"I owe just about everything to John Avildsen. His directing, his passion, his toughness and his heart - a great heart - is what made 'Rocky' the film it became," Stallone wrote in a statement.
"He changed my life and I will be forever indebted to him. Nobody could have done it better than my friend John Avildsen. I will miss him."
Another underdog film, "The Karate Kid," was also an unexpected success at the box office and spawned a series of films, a sequel and a remake.
The 1984 film tells the story of a teenager hounded by bullies, who learns karate from a Japanese handyman and takes on his bully in a karate contest - and wins.
In a 1992 interview, Avildsen outlined his view of filmmaking. "I don't see my films as following any strict formula - even if many of them do have a similar theme," he said. "I guess I just like to see underdogs winning against the odds. To me, that is good drama. And the opposite would be too depressing."
Avildsen is survived by his sons Jonathan, Ashley and Anthony, and daughter Bridget.
aw/cmk (AP, dpa)