Following the race Red Bull has revealed that Ricciardo secured the Monaco Grand Prix top podium with a car that was 25% down on power, following suffering an MGU-K failure early in the race.
After the 20 laps of 78-lap street race, Ricciardo reported a sudden power loss which the team immediately attributed to an MGU-K failure.
“He has lost about 25% of the power of the engine,” Horner told Sky. “And then because of the way these engines work, his rear brake temperatures are going through the roof.
“We saw it with Lewis Hamilton and Nico Rosberg a few years back in Montreal.
“He is having to cool the brakes, he is having to cool the car, he is having to lift off to do that. He is having Sebastian Vettel breathing down his neck. He cannot make a mistake. He cannot lock a wheel up.
“He is dealing with all the switch changes and all the stuff that he has got to manage. And he totally nailed it. He was the coolest guy out there today.”
The Australian found himself only able to use six gears because it did not enough power to get up to seventh.
“It was unbelievable,” Horner added. “He was not going to give this race up, this weekend. He has been quickest in every session. We lost the MGU-K 17-18 laps into the race, and that is 2.5 seconds per lap he is giving up.
“Then your brake temperatures go out of control, the fuel, tyre temperatures go up – and he just managed it like he was on a Sunday afternoon drive.
“They are telling me on the intercom that we are going to have to retire the car after one or two laps, and I said look, we are in the lead of the Monaco GP, we are keeping going.
“Moving the switches around, driving, saving fuel, saving brakes, saving tyres, asking what was going on with Max’s tyres and everything else, he drove an unbelievable race this weekend.”