Earls’ score at the Olympic Stadium was his eighth in World Cups, making him Ireland’s top try-scorer in the history of the tournament, while fly-half Johnny Sexton kicked 11 points to hold off a spirited Italy.

Ireland are guaranteed to reach the knock-out stages and will play France next Sunday to decide who finishes top and likely avoids champions New Zealand in the last eight.

Defeat ends Italy’s chances of progress but Jacques Brunel’s side can take heart from a determined performance, which stretched a team many believe represent Europe’s best hope of becoming champions.

Italy tried to peg back their opponents once more but substitute Carlo Canna fell short with a long-range penalty before Ireland’s O’Mahony was handed a yellow card for shoulder-charging a ruck.

Down to 14, Ireland looked nervous in the game’s final minutes as Sexton skewed a fairly straight-forward penalty wide and Italy piled forward in search of the match-saving try.

The opening never came, however, as Ireland held on for a narrow victory and set up a thrilling pool decider with the French.