This is not unlike Alonso's teammate Stoffel Vandoorne's decision to hit the treadmill during the race when his McLaren blew up in Bahrain.
Max Verstappen, the 2016 victor at a record age of 18, and fellow Red Bull driver Daniel Ricciardo will start the race from fifth and sixth on the grid.
Fernando Alonso has confirmed he will keep the auto he will use to compete at the Indy 500 later this month.
Just when McLaren had nowhere to go but up, it sank to a new low when Fernando Alonso's vehicle broke down on Friday's first lap of practice for the Spanish Grand Prix.
Honda's F1 engine is said to be about 120bhp behind the pace-setting Mercedes and Ferrari units, which produce close to 1000bhp, and there are widespread rumours that Mercedes are to assist Honda with their engine technology in an attempt to help the Japanese company catch up.
Alonso is yet to see the chequered flag this season, having retired from the first three races of the year and failed to start last time out in Russian Federation.
Alonso is enduring a wretched start to the season.
McLaren are yet to score a point in four races.
"We knew we needed to put the flawless lap together", he said.
White smoke enveloped the two-time Formula One champion when his McLaren spun out of a turn and into the gravel at the start of the morning session at the Circuit Barcelona-Catalunya.
"Yes, that is what is going to happen", said Alonso. "Definitely, our moment right now is not the best".
"We need to raise our game and hopefully finish with both cars this weekend", he said. "So, I hope this will be the starting point of a new championship for us". "Two intense weeks ahead, but pretty much looking forward".
"So I think from the chassis side we more or less confirmed what we thought at the beginning of the year and the first races - that we are quite competitive and we are happy with the things that are happening on the chassis side".
"If from here to September, or October, I see an opportunity to win in 2018, I'll be more than happy to stay". At the end of the day, I felt a little bit more comfortable.
The 35-year-old Alonso ranks sixth all-time with 32 wins, but his last victory came at the 2013 Spanish GP while he was with Ferrari.
The team are doing their best to persuade Alonso to re-sign and have put together a programme for him to compete in the Indianapolis 500 later this month.