Alonso qualified fifth for the race on Sunday despite having never driven an Indy car before this month

Fernando Alonso says he expects to find the Indianapolis 500 "difficult" as he attempts to win the prestigious race for the first time on Sunday.

The McLaren Formula 1 driver is missing the Monaco Grand Prix to race in the US and has qualified fifth on the grid.

"Anyone can win the Indy 500 of the 33 drivers because it is an unpredictable race," the 35-year-old said.

"You cannot plan in advance. You need to keep improvising. I know I will lack experience in critical moments."

The Spaniard said he was determined to enjoy the event.

"I want to live the moment, I want to live the experience," said the two-time F1 world champion.

"On Sunday when race time arrives, 300,000, 400,000 people at a sport event has no comparison to any other sport event in the world.

"The Olympic Games and Super Bowl cannot put 400,000 people in one place on one Sunday."

Hundreds of thousands will attend the event held during Memorial Day weekend in the US

Alonso said he was "surprised" by his speed in qualifying, which puts him in the middle of the second row for the rolling start.

And he could have been faster - a brief engine problem during his four-lap qualifying run cost him a place on the three-car front row.

"When we announced to come here one month ago, we did it without knowing how competitive we could be, if I was able to adapt to oval racing, to these cars," said Alonso, who is driving a McLaren-branded car for Andretti Autosport team, powered by an engine made by McLaren's F1 partner Honda.

"You respect the place, respect the speed. You respect your colleagues out there but at the end of the day, when you are in your car and close the visor, you would like to have one mile per hour more. It's never enough."

Alonso said he felt his biggest handicap in the race would be his lack of experience of running in groups of cars at speeds of 230mph.

The biggest challenge I will face is in the race when you are running in traffic, those groups of cars that form in the race," Alonso said.

"It changes completely the behaviour of the car. You feel the car very loose... we've been practicing that with the team, trying to create our own groups because we are six cars.

"With no experience, for me you're not sure sometimes where you are with that line - if you are over the limits of the car, or over the limits of running with the traffic. Just guessing what the car will do, what you are doing.

"I still lack experience in important moments of the race. I will try to compensate with the speed, with motivation and we will see what happens.

"Taking the opportunity to overtake and to pass will be a difficult decision to make. There are many factors you need to address while you are driving 230 miles per hour.

"You have to stay calm, be ready for the last one-third of the race. That is where it comes."

New Zealander Scott Dixon will start the race from pole position

Dixon expects Alonso threat

Alonso had never driven an IndyCar before his 'rookie' test on 4 May, but four-time IndyCar champion Scott Dixon, who has qualified on pole, believes the F1 driver will be a threat for victory in the race.

"He's done amazing and to be honest, to win the race, he's going to be one of the guys you're going to have to beat," the 36-year-old New Zealander said.

"You can typically weed out a group of guys in any formula that are at the top and are slightly different than the rest and he is one of those guys."