The tennis court was in a billionaire's backyard overlooking a secluded cove on Lake Zurich. It was an unexpected location to be playing the world's top ranked male tennis player, Roger Federer. Between rallies, 29-year-old Brisbane boy John Millman gazed up at the splendid home of Jorge Lemann, founder of 3G Capital, the company that partnered with Warren Buffett's Berkshire Hathaway to buy Burger King and Heinz. Finally, he was playing with the heavy hitters, he thought.

That evening they dined under the high polished wood ceilings of the Grasshopper Restaurant in one of the oldest houses in Zurich. The Fed had his trademark Swiss sausage salad. The whole experience proved to be an educational one for Millman because months later he drew on it to beat Federer, the 20-time grand slam champion, in a gruelling four sets at the US Open in September 2018.