Australia lock Rory Arnold will miss his country's first test against Ireland as he has been suspended for three weeks after being shown a red card in the Brumbies' 42-24 Super Rugby loss to the Lions.

Arnold, who had already spent 10 minutes in the sin-bin in the first half, was shown a straight red card for a dangerously high tackle on Lions flyhalf Elton Jantjies.

Arnold had a potential six-week ban reduced to three weeks because of his previous clean record.

"A dangerous high tackle, merited a mid-range entry point of six weeks," SANZAAR, the body which operates Super Rugby, said in a statement.

"However, taking into account mitigating factors, including the player's excellent, clear, disciplinary record, his expressed remorse and his guilty plea at the first available opportunity, the Foul Play Review Committee reduced the suspension to three weeks, up to and including Saturday, June 9, 2018."

Australia will therefore start their three-match home series with Ireland on June 9 without Arnold, but his reduced ban means the 27-year-old could return for the final two games