It's a huge endorsement from the retired wide receiver who won two Super Bowl rings with football legend John Elway, has two sons now playing in the NFL, and another two regarded as very bright junior prospects.

The sport's exposure down under has come a long way since McCaffrey played a pre-season match with the Denver Broncos against the San Diego Chargers in Sydney back in 1999.

For many years Australia's interest in the NFL was fleeting, limited for most to Madden video games and the Super Bowl.

But now interest is booming and Australia will get another taste of American football when Stanford University play Rice University in the college football Sydney Cup at Allianz Stadium on August 27.

McCaffrey was in Sydney to launch the Sydney Cup alongside fellow Stanford Cardinal alumnus and the NFL's No. 3 draft pick Solomon Thomas, who lived on Sydney's north shore for five years as a kid.

Thomas joined the storied San Francisco 49ers - the franchise at which McCaffrey won one of this three Super Bowl rings, and the same team NRL star Jarryd Hayne played for.

Thomas is the latest NFL player with an Australian connection, following punter Sam Irwin-Hill's signing with the Dallas Cowboys.

Irwin-Hill's parents live in Canberra, a city that is starting to punch above its weight in the Australian gridiron production line.

Canberra boasts four representatives in Australia's under 19 gridiron squad with James Thornhill and Dale Haskew joining 16-year-old sensations Lachlan French and Luke Deutsch.

Australia stood up and took notice of Hayne's stint and McCaffrey believes he has laid the foundations for more international players to reach the top level.

For years the only pathway to the NFL has been through college football, but McCaffrey believes Hayne bucked the trend and opened up more opportunities for his countrymen.

"I wonder when I look at athletes like that that have success in the game, I wonder what he would have been like had he grown up in the States and played American football his whole entire lifetime," McCaffrey said of Hayne.

"He probably would have been more prepared. He came on the scene pretty late but he still, because of the type of athlete he is and his dedication, was able to have success in the NFL.

"It's very much thought of as an American sport but I've seen a handful of players from Australia make it into the NFL in the last couple of years.

"The similarities in terms of the physical attributes necessary to play football, rugby, or Australian rules football are very similar.

"I think physically there are players here in Australia and around the world that are capable of playing in the NFL.

"Many of them haven't had the instruction throughout their lives to be able to compete even if they have the athletics ability, but I think now with the sport expanding across the globe they're now able to get some better instruction so that if it's something they want to do, they're better prepared."