Fernando Alonso doubts Ron Dennis would've let him enter Indy 500

Alonso announced his shock decision to make his IndyCar debut with Andretti Autosport ahead of this weekend's Bahrain Grand Prix.

The plan has the full backing of McLaren's new executive director Zak Brown, with the organisation hinting at a wider IndyCar involvement in the future too.

But asked if former McLaren chairman Dennis would have let him miss Monaco for Indy, Alonso replied: " I guess not.

"Zak is a man that has a bigger vision than other team principals or bosses that I had.

"He sees motorsport differently, he sees McLaren bigger and no longer concentrated on F1.

"He is a true racer, so it is great that McLaren had Zak come on board last year."

Alonso admitted that McLaren-Honda's current lack of competitiveness in F1 made the decision to miss a grand prix easier.

"If the car was competitive this year and we were on 43 points together with the other guys [leading the championship], you cannot afford to lose a 25 points possibility missing one race," he said.

"Things would be different if we were competitive."

The double F1 world champion has openly admitted he sees his Indy 500 bid as part of an attempt to win a 'triple crown' of motorsport's biggest events.

Alonso won the Monaco GP in 2006 and '07, and has long hinted at Le Mans 24 Hours ambitions too.

He revealed that a Le Mans offer for this year was "on the table" too before Indianapolis was prioritised.

"Because Zak is American he was pushing for the Indy 500, and Eric [Boullier] French pushing for Le Mans," said Alonso.

"The McLaren-Honda partnership, to be able run this in Indy 500, was very attractive this year.

"Le Mans is something I will do, probably as soon as I can.

"I don't know if it will be next year or in the following years.

"The first priority is F1.

"If I can race together with F1 and other series as I am doing this year it will be OK. If not I will only do F1."