Jenson Button has slated McLaren team-mate Sergio Perez as "dirty" and "dangerous" and fears the Mexican will cause an accident unless he learns to calm down.
A week after team principal Martin Whitmarsh called for Perez to "toughen up" and "get his elbows out", Perez overstepped the mark. In a Bahrain Grand Prix won at a canter by Red Bull's reigning world champion Sebastian Vettel, all the action happened behind the German, notably involving Perez.
For a number of laps the McLaren duo duked it out, with Perez at one point clipping the back of Button's right-rear wheel, losing a small part of his front wing in the process, and Button said: "I've had some tough fights in F1, but not quite as dirty as that. Something serious will happen soon, so he has to calm down."
He added: "What he did are what you do in karting and normally you grow out of it, but that's obviously not the case with Checo."
What Whitmarsh would not have anticipated when he spoke to the 22-year-old following last Sunday's race in China was that the primary recipient of Perez's new-found fortitude would be Button.
Worse for Button, even though he could have gained a puncture from such an incident, was when Perez banged wheels with the 33-year-old at the end of the main straight at the Bahrain International Circuit.
Come the chequered flag, Perez at least produced his best result for McLaren of sixth, while Button had to settle for 10th as for once he endured tyre trouble and needed to pit on four occasions.
Button was far from happy with Perez, and said: "There was a lot of clean racing, which was good - apart from with my team-mate. I've raced with many team-mates over the years, and I had quite an aggressive team-mate in Lewis (Hamilton).
"But I'm not used to driving along a straight and having a team-mate coming alongside me and wiggling his wheels at me, and banging wheels at 300 kilometres an hour.
"That isn't normally the way I go racing. It's a new thing to me. Maybe it's the way we go racing now, but it's not the way I want to. He touched me from behind and he touched me on the side going in a straight line at 300 kilometres an hour. That's dangerous. I don't really enjoy that."