Motor racing - Triple crown: Monaco or F1 championship?

May 18, 2017; Indianapolis, IN, USA; Verizon IndyCar Series driver Fernando Alonso pulls out of the pits during practice for the 101st Running of the Indianapolis 500 at Indianapolis Motor Speedway. Mandatory Credit: Brian Spurlock-USA TODAY Sports

LONDON (Reuters) - If Fernando Alonso were to beat the odds and win the Indianapolis 500 on May 28, the double Formula One world champion will be one step away from the 'Triple Crown of Motorsport'.

That much is certain. But there is still some debate about what three jewels actually feature in a crown only ever worn by one man.