Fernando Alonso has labelled his first day at an Indianapolis 500 meeting as a “good day” despite his running being cut short by suspension problems.

While passing the rookie orientation program nearly a fortnight earlier, Alonso partook in the two-hour session for rookies and refreshers, setting the fastest time of the 13 participants with a 40.6074s lap.

When the rest of the field was allowed on-track for the four-hour Practice 1 session, the two-time Formula 1 world champion improved to a 40.3543s.

The effort put Alonso 19th fastest, within 0.6s of pace-setting Andretti Autosport team-mate Marco Andretti.

“It was a good day,” said the Spaniard.

“I was a little bit concerned about the conditions, (it was) much hotter today than the test we did here on the third (rookie orientation/private test) but the car felt good, as good as in the test.

“I was able to make some setup changes without losing the confidence in the car. Everything went very smooth.

However, Alonso logged the third-lowest mileage of the 32 runners during the open practice session, his 20 laps just under half the average.

The 35-year-old confirmed that suspension issues in the McLaren-entered Honda had curtailed his Day 1 program and prevented him from gaining his first real experience of traffic on the superspeedway.

“The last half an hour maybe we had some issues with the rear suspension, and we could not complete the program.

“We were planning to run a little bit in traffic at the end of the day, so we missed that part, but overall it was an amazing day.

“(I’m) Happier than the first day with the car because I was able to feel some of the setup changes that we were planning in the morning, and I feel good.

“(I had) Not much running in traffic, so that is still the thing that I need to go through in the next couple of days, something we need to chase tomorrow in the program.

“But I did two or three laps behind some cars that were going out of pit lane, and it was good fun, so I’m looking forward to it.”

The McLaren Formula 1 driver had finished 12th in the Spanish Grand Prix in Barcelona just a day earlier before heading directly to Indianapolis, but said that he quickly became accustomed to the IndyCar and the circuit which he had only driven for the first time 12 days earlier.

“It took one corner,” he explained.

“I think with the test we made on May 3rd, you switch on quite quickly.

“You jump in the car, you are in that seating position that is different compared to Formula 1. You just remind yourself exactly what you were driving two weeks ago, so you go flat out and you know what is going to happen.

“It took really no time to switch on from one to another.”

Practice continues on Tuesday morning at 0200 AEST with qualifications starting on Saturday local time.