Australia's impressive pair of rookie locks are eager to lock horns with Scotland's towering brothers Jonny and Richie Gray in their latest Test rugby examination.
The pair are the seventh lock combination tried under coach Michael Cheika this year, but have taken to the international arena with consummate ease - despite boasting a collective 15 Tests heading into Saturday's clash with Scotland.
The pair nullified Wales veteran Luke Charteris last weekend, but are acutely aware that British and Irish Lions representative Richie and his rising star brother Jonny are a fearsome prospect.
"The two Gray brothers ... there's some tall timber there," said Arnold, who at 208cm is a giant in his own right.
"I'll be looking forward to it. They've established themselves as good locks over the past few years.
"I'm looking forward to this weekend and I'm sure if I'm given the opportunity that I'll be able to take that on."
Scotland have identified the lineout as an area they need to control, with defence coach Matt Taylor signalling an intention to spoil and challenge Australia's young star pairing to deny the Wallabies' in-form backline a chance to shine.
The 26-year-old Arnold took Taylor's words as a personal challenge for he and Coleman to take on.
"Especially if they come at the lineout - it's our sort of area, we've got to run and if we get good fast ball there then it sets up our platform for the backs," he said.
"They're a good team at the breakdown as well so they'll be trying to slow down all our sort of multi-phase shape so we'll have to be good around the breakdown too."
And while the lineout is where Coleman and Arnold will be judged, their devastating ball carrying against Wales - where they combined for 120m, the most run metres by an Australian lock pairing in a match since 2010 - is also an appealing aspect of this new combination.
Arnold, who ran for 52 metres, said it's an aspect of the game which excites him.
"We both like carrying the ball," he said.
"It's always good to get your hand up and your hands on the ball, and have those hard carries."