A "Tell Penske to go f**k themselves" radio message was just the latest installment in bubbling IndyCar animosity between Arrow McLaren and Team Penske.

It's mainly between two of their drivers - Nolan Siegel at McLaren and Penske's Scott McLaughlin - but the ‘beef' hasn't stopped there.

After Siegel's outburst, Arrow McLaren felt the need to issue a statement condemning its young driver's behaviour. Here's how the story unfolded and why its roots are in a bigger conflict that's more than just the two drivers.

What happened?

On lap 83 of the Gateway race last weekend Siegel was desperate to stay on the lead lap. Leader McLaughlin dived to the inside on the exit of Turn 2 to make a move and Siegel pushed McLaughlin down the track and below the white line.

IndyCar's rulebook states you can't make a move in defence in reaction to another driver's attack.

Siegel was given a drive-through for contravening this rule which is labelled ‘blocking', and is even more strictly enforced on ovals to avoid massive accidents from drivers being too aggressive in defence.

This came a race after Detroit, where McLaughlin hit Siegel while trying to overtake him at Turn 1. A whole X back and forth then ensued between McLaughlin and McLaren's team principal Tony Kanaan. More on that shortly.

After the move at Gateway, Siegel cursed repeatedly on the radio, and this was brought to the attention of many fans via an onboard video shared by the excellent IndyCar account, @indy44, on Tuesday.

In reaction to the penalty for blocking, Siegel said: "Bulls**t, f***ing bulls**t, absolutely not.

"Absolutely not, you f***ing take me out last race and he gets to f***ing continue. No. F**k that s**t. Tell Penske to go f**k themselves."

In a later discussion with his team, Siegel added: "I want you to talk to them about that penalty. That's f***ing bulls**t", to which his team replies, "10-4, we'll deal with it after the race".

"Deal with it right f**ing now," Siegel concludes.

What has happened in the aftermath

Siegel has apologised via a video on his Instagram account, McLaughlin has confirmed he and Siegel have cleared the air, and McLaren issued a statement condemning the language and nature of Siegel's tirade.