Michael Johnson once made sprinting look like an eclectic art form, with his stiff upright running stance and short steps powering him to four Olympic golds and eight world titles in the late 1990s.
A sporting icon in every sense of the word, even the American - who still holds the world and Olympic records in the 400m - is in awe of the feisty and frenetic sport of rugby sevens.
The 48-year-old admits to being a big fan of the fast-rising United States team.
Led by speedster Carlin Isles, the Eagles won the London Sevens in May to finish sixth out of 15 nations in the 2014-15 HSBC World Rugby Sevens Series.
Johnson gets a front-row seat to the hard-hitting action as a special guest at this weekend's season-opening Dubai leg. The National Stadium in Kallang hosts the popular global series from April 16-17, the eighth of 10 legs.
"It's such an interesting sport, seeing these athletes using speed, power and multi-directional movement to blow past opponents," Johnson told The Straits Times during a phone interview yesterday.
"I ran fast but these guys are doing it with a ball and others chasing after them. Now that's impressive."
Johnson's own CV is also a shining one.
He is the only male athlete in history to win both the 200m and 400m dashes at the same Olympics, a feat he accomplished in Atlanta in 1996.
The Dallas native is also the only man to retain his Olympic title in the 400m.
Like the rest of the sporting world, Johnson is eagerly awaiting Rio 2016.
Besides rugby sevens making its Olympic debut, other talking points include sprint king Usain Bolt aiming to sweep the 100m and 200m golds for a third successive edition, and 18-time gold medallist Michael Phelps' return to the pool.
Each sport has its world championships, World Cups and all-star invitationals. But for Johnson, nothing comes close to matching the atmosphere and array of talent assembled at the quadrennial Olympics.
He explained: "In a historical sense, the Olympic Games have always been the pinnacle of sport.
"You are training for years for that one significant moment.
"Get the gold, and you become a king or queen. Lose, and it's a painful four-year wait."