Red Bull has revealed Daniel Ricciardo lost 25 percent of his Formula 1 Renault engine after less than 20 laps en route to winning the Monaco Grand Prix.

Ricciardo led away from the dominant pole position he sealed on Saturday and led throughout the opening stint, but reported a sudden loss of power shortly after his pitstop.

That allowed Ferrari’s Sebastian Vettel to close in on Ricciardo, but the Australian held on despite his power unit problems - which left him around 12mph down on his rivals in the final sector alone - to claim a redemptive victory in Monaco.

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Following the race, Red Bull team principal Christian Horner revealed the true extent of the Australian’s issues, explaining that Ricciardo lost complete use of his MGU-K - the engine component that returns harvested energy from the MGU-H to the car’s drivetrain - costing him as much as two and a half seconds per lap.

“He was not going to give this race up this weekend,” Horner told Sky Sports F1. “He lost the MGU-K 17 or 18 laps into the race. That’s what it was.

“That’s two and a half seconds a lap he is giving up. He’s lost about 25 percent of the power of the engine and because of the way these engines work, that’s making his rear brake temperatures going through the roof. He’s having to cool the brakes, he’s having to cool the car, he’s having to lift off to do that. 

“He’s got Sebastian Vettel breathing down his neck, he cannot make a mistake. He cannot lock a wheel up. He’s dealing with all the switch changes, all he’s got to manage and he totally nailed it. He was the coolest guy out there today.”

Horner admitted Red Bull feared it would be forced to retire Ricciardo’s RB14 but said the team was determined not to give up on its chances of claiming a first Monaco win since 2012.

“They were telling me on the intercom that we were going to have to retire the car in one or two laps and I said look, we’re in the lead of the Monaco Grand Prix, we’re keeping going.

“He was moving the switches around, driving, saving fuel, saving brakes, saving tyres, asking what’s going on with Max’s tyres and whatever else. He drove an unbelievable race this weekend.”

Red Bull motorsport advisor Helmut Marko said he believes no other driver would have been able to manage the situation and still win around Monte Carlo’s notoriously challenging streets.

“It was a serious problem and he managed it unbelievably,” Marko explained. “I don’t think any other driver could have done it.

“[We were] very nervous because in the beginning it looked like could even push the car further car but then he changed the set up, changed his driving style so  it was unbelievable.”