Red Bull revealed that Max Verstappen suffered a radio communication failure after the final restart on the Canadian Grand Prix, with the Dutchman unable to speak to his team.
A Safety Car triggered by Yuki Tsunoda's crash on lap 47 of 70 handed Ferrari's Carlos Sainz, who was leading the race at that moment, an opportunity to pit and rejoin proceedings right behind Verstappen but on a fresher set of tyres.
The shootout produced a thrilling finale between the two drivers but one that left Red Bull race engineer Gianpiero Lambiase without a word from Verstappen as the driver-to-team communication suddenly went quiet.
"There was just one-way traffic from GP to Max, just giving him the gaps, but nothing coming from the car," explained team boss Christian Horner.
"It turns out that the radio wasn’t working, or certainly he could hear us but we couldn’t hear him."
Verstappen wasn't sure when his radio had failed but said the breakdown had been inconsequential.
"It didn’t work any more, it decided to stop," he said. "I have no clue when it stopped, but at one point, GP told me it was not working any more, I think on the inlap after the line.
"I guess it must have been working before, or it already didn’t work before, which probably they didn’t mind! As long as I can hear him, that’s the most important thing."
Verstappen admitted that he wasn't sure that he would be able to catch Sainz when the Spaniard was leading the race with an eight-second advantage, while the deployment of the Safety Car also through his hopes of winning in doubt as he knew that Sainz would be snapping at his heels armed with fresher rubber.
"I was not sure if I actually would have fully closed that gap to the end of the race," Verstappen said.
"Then the safety car came out, and I was also not very happy with that, because I knew he would have fresh tyres behind me, and already I think with a little bit more pace compared to me, it was difficult to defend.
"The last 15, 16 laps, we were flat out, pushing to the limit, and I knew of course I couldn’t make a mistake.
"It was good racing. It’s always more enjoyable to be able to push in a Formula 1 car instead of just saving your tyres."
Horner also admitted that the race's final ten laps had been a gripping affair for the Red Bull pitwall.
"It wasn't very comfortable at all in those last 10 laps or so after that VSC," he told Sky Sports F1.
"Because Max just couldn't break the DRS and the Ferrari was very quick on the straight line today. They could attack the kerbs and stay close.
"But not a single mistake."
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