The questions are now being asked if this is the right decision for a driver who is widely regarded as one of the best in the current GP era, and whether this could have long-term ramifications on his career.

Alonso has started in 276 Formula One races, winning the world title in 2005 and 2006. He has won 32 races, scored 97 podium finishes and 22 pole positions, so clearly he is an outstanding driver.

While they are impressive statistics, stepping into the world of Indy car racing will require more than skill as the disciplines could not be more different.

For a start the Indianapolis track is a four-kilometre rectangular shape that has four, slightly banked left-hand turns, and to be competitive, a driver needs to consistently lap at an average speed in excess of 300km/h.

Slip-streaming on the straights in the 33-car field is an art in itself, and while it happens in Formula One, it’s nowhere to the same extent and requires lightning reflexes and bravery to make a pass.

The cars themselves are significantly different with the 2.2 litre, V6 twin turbocharged Chevrolet and Honda engines producing 550 to 700 horsepower depending on boost, and they are heavier than an F1 car at a minimum weight of 718 kilograms.

The race will last for about three hours, depending on safety car periods, so Alonso will be in the car for 50 per cent longer than he would in a F1 race.

Despite being a two-time world champion, Alonso will be required to go through a rookie test programme before going into the practice and qualifying sessions which take up most of the month of May.

The grid is limited to a maximum of 33 cars irrespective of oversubscribed numbers, so just getting a start in the race will be a big ask.

So why does Alonso want to do this and why has McLaren Honda giving it’s blessing?

It should be remembered that since joining McLaren Honda, after leaving Ferrari at the end of 2014, Alonso has endured the most results-poor and frustrating period in his F1 career which commenced in 2001 with Minardi.

In 42 F1 races for McLaren Honda his best finish has been a fifth place in Hungary in 2015 and another fifth place at Monaco in 2016, but there have been twelve retirements and mostly back-of-field results.

The Spanish driver has been extremely vocal about the lack of performance from the Honda power unit, and his frustration has boiled over at times resulting in some less-than-favourable comments over the team radio.

It would seem that this opportunity to drive for the Andretti Autosports team in the Honda-powered Dallara is something of an olive branch from McLaren to allow Alonso to try and achieve a long-held ambition.

In 1966 the late Graham Hill won the Indy 500 to become the first driver to win at the famous brickyard to back up wins in the F1 world championship and the Le Mans 24-hour sports car race.

Much has changed in the past 50 years and the question is can a rookie win at Indianapolis?

Since the first race in 1911, only nine rookies have won at Indy, including last year, when ex-F1 driver Alexander Rossi drove a Honda-powered car to victory for Andretti Autosports, so there is a precedent.

The Michael Andretti-run team won the 500 in 2005, 2007, 2014 and 2016 and they won the Indy series in 2004, 2005, 2007 and 2012, so there is a great deal of winning success behind the effort.

At least as far as strategy calls are concerned, the experience gained during the years by Andretti Autosports will be a plus for Alonso, but clearly it’s going to be big ask to expect a win. Then again Alonso is an exceptional racer.