A combination of Ryan Baird's 21st-minute red card and a luckless spate of injuries left the Ireland Under-20s exposed down the final stretch as Australia ruthlessly took advantage to claim a 45-17 bonus point win in Santa Fe.

Romain Ntamack, son of former French star Emile, led the way as France opened their Six Nations campaign with a win but only after they held off a spirited Irish recovery.

A stirring second-half fightback from the Ireland Under-20s fell short as fortune favoured France in a 34-24 Six Nations win for the hosts in Bordeaux.