With 19 minutes played, smart work from Connacht centre Robbie Henshaw enabled Earls to cross the whitewash and overtake GUINNESS PRO12 legend Brian O'Driscoll as Ireland's all-time leading World Cup try-scorer.
Three penalties and a conversion from Leinster new boy Jonathan Sexton were the only other points for the men in green as an Italy starting XV sporting eight GUINNESS PRO12 players battled valiantly.
Flanker Simone Favaro, who made the move from Benetton Treviso to Glasgow Warriors over the summer, was particularly impressive while Munster back-rower Peter O'Mahony's try-saving tackle on Josh Furno just after the break helped secure the victory.
Ireland now face a showdown with France next Sunday to decide who tops Pool D while Wales face the same scenario in Pool A when they square off with Australia on Saturday.
The boot of Ospreys fly-half Dan Biggar provided 13 points as Wales edged past Fiji 23-13 at the Millennium Stadium which, combined with Australia's 33-13 triumph over England, secured Warren Gatland's troops a spot in the last eight.
Scarlets scrum-half Gareth Davies got the show on the road against Fiji as he threw an outrageous dummy on seven minutes to score the opening try before Ospreys hooker Scott Baldwin squeezed over for a second later in the first half.
It wasn't a vintage display from Wales but Biggar's metronomic kicking kept the Pacific Islanders, and Glasgow Warriors lock Leone Nakarawa, at arm's length.
Elsewhere, Warriors winger Tommy Seymour's try wasn't enough for Scotland on Saturday as South Africa, for whom Ulster scrum-half Ruan Pienaar came off the bench, won 34-16 at St James' Park to move top of Pool B.
Also in Pool B, Treviso lock Filo Paulo couldn't stop Samoa falling to a disappointing 26-5 at the hands of Japan in Milton Keynes on Saturday.
And Scarlets flyer DTH van der Merwe notched his third try of the tournament but his Canada side, skippered by Ospreys No.8 Tyler Ardron, ultimately went down 41-18 to France in Pool D.
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