Charles Leclerc was unable to start the Monaco Grand Prix due to a gearbox problem.
Ferrari confirmed that Leclerc, who was due to start on pole despite a crash in qualifying, would not be starting the race.
"We have an issue and we will not make it to the grid,” a member of the Ferrari team confirmed to FIA director Michael Masi.
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Leclerc appeared to hit trouble as he was making his way to the grid, and parked up in the Ferrari garage visibly upset with his head in his hands.
Red Bull’s Max Verstappen starts on pole with championship rival and current leader Lewis Hamilton down in sixth.
Leclerc still attended the pre-race ceremony and received a hug from Prince Albert.
"I am surprised because they checked the gearbox," said Mercedes boss Toto Wolff.
"It's also a shame because he's Monegasque, people are cheering for him and he deserved it (pole) because his lap was spectacular.
"For us, Max mustn't score 25 points. That's not good for us. So we would have hoped that Charles stayed in the lead but let's see what opportunity it gives for Valtteri."
Leclerc has yet to finish a home grand prix, with the showcase harbourside race not held last year due to the Covid-19 pandemic.
He retired after collisions in 2018 and 2019. The Monegasque also failed to finish two Formula Two races there in 2017.
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