Ricciardo's Monaco MGU-K was not properly bolted on!

It was squeaky bum-time for Daniel Ricciardo when his MGU-K unit broke down halfway through the Grand Prix, and Red Bull advisor Dr Helmut Marko has now revealed what the cause of the problem was.

When Ricciardo communicated over the team radio that he was losing power, many thought that that was it for the Aussie. Another Monaco Grand Prix where he was in the lead but got technical problems. Not this time, though. He fought off Sebastian Vettel and limped to the finish line in P1, getting redemption for the pit stop drama that cost him the race in 2016.

"Everybody was afraid that that one lap could have been the last," Marko tells Auto Motor und Sport.

"We didn't know what had happened exactly, and every defect can damage the engine."

Luckily for Ricciardo and the Bulls, there was no permanent damage on either the engine or the MGU-K. The problem was that the part didn't get bolted on properly.

"We now know that the MGU-K didn't break, but that it was put on the car sloppily."

That could have been a very costly mistake.