Sebastian Vettel was heard venting his anger at Narain Karthikeyan over the team radio during the 2012 F1 United States Grand Prix, after the HRT driver featured in the decisive moment of the first race to be held at the new Circuit of the Americas.
In the latter third of the race, Vettel had been coming under increasing pressure from a charging Lewis Hamilton who was within DRS activation range of the Red Bull. Vettel saw the danger, and while he fended off the threat once on the previous lap, his freedom to manoeuvre was hampered on lap 41 by the presence of Karthikeyan's slow car in the run down to turn 11.
"I wasn't too happy to send a nice big invitation to Lewis when I had to go through Karthikeyan," Vettel told the press after the race.
"[Hamilton] took that opportunity, fair enough, down the straight and he passed me," he continued "I tried to defend but I knew he would have so much more speed. I was obviously not too happy.
"Lewis had one chance and he took it," he said. "After that I tried to stay with him but there wasn't much between us."
The team needed to settle Vettel down after the incident, and after he'd vented his anger over Karthikeyan was calmly advised: "We saw that, but keep your focus on the job in hand."
Red Bull team principal Christian Horner clearly sympathised with his driver's disappointment at the lost win. "Well done Seb, that wasn't your fault," he radioed to Vettel on the cool-down lap.
"The race unfortunately hinged on one backmarker that didn't use his mirrors," he went on to explain to Sky Sports F1
. That was the difference. It cost Sebastian vital time and it gave Lewis a clear and easy run under the DRS.
"There was nothing between the two of them today, they were trading times all afternoon, and it was that one backmarker that cost us," he continued.
Karthikeyan also clashed with Vettel in Malaysia early in the season, with the HRT cutting Vettel's back wheel in an clash during the race. Given that the drivers championship goes down to the season finale with only 13pts between Vettel and Fernando Alonso, it's entirely possible that Karthikeyan's interventions could swing the title outcome.