Italy fly-half Allan kicked the other points with Noel Reid and his replacement Ciaran Frawley booting a penalty apiece for Leinster.

Leinster improved on the resumption and twice drew level, with tries from James Lowe and replacement Bryan Byrne sandwiching Federico Ruzza's 53rd-minute effort.

The impressive Frawley slalomed over for a classy 70th-minute score, which he converted himself, but the Italians' persistence was eventually rewarded as they moved within two points of second-placed Ulster in Conference B.

It was an attritional opening 40 minutes for Leinster, who lost both Reid and Mick Kearney to injury.

A couple of sloppy penalties, with Conor O'Brien and James Tracy infringing at rucks, invited the visitors forward and they hit the front from their first line-out opportunity, Bigi breaking from a maul to score to the left of the posts.

Allan converted before a Reid penalty opened Leinster's account, rewarding a fine midfield break by Barry Daly.

Leinster responded well to a well-struck Allan penalty for 10-3, full-back Daly posing a threat again before Joe Tomane was put into space on the right and scrum half McGrath was desperately close to collecting the centre's kick over the try line.

A subsequent penalty allowed Reid's replacement Frawley to split the posts from close range.

With scrum-half Dewaldt Duvenage orchestrating things, Benetton had a couple of prolonged bouts of forward pressure approaching the interval, the home defence holding out until Allan tapped over three more points, but Leinster erased that lead just seven minutes into the second period.

McGrath's quick tap led to the influential Max Deegan hammering up to just a few metres out, and then the scrum half's rapid delivery from a ruck allowed Lowe to wriggle out of a double tackle and crash over to the right of the posts.

Frawley equalised from the tee, but Benetton were swift to respond, carrying through 25 phases before lock Ruzza barged over from close range.

A well-executed line-out drive propelled Byrne over as the momentum swung back to Leinster with just over 15 minutes remaining. They rode their luck at times, Fergus McFadden fortunate that an 'unlucky' clearout, in referee Nigel Owens' words, did not result in a penalty reversal and a yellow card.

Indeed, from the penalty to touch, a crisp backs move saw O'Brien's deft pass send Frawley scurrying over for his seven-pointer.

However, there was still enough time for Benetton to build some late pressure, with a forward pass from Lowe handing them possession and field position.

Leinster's youngsters stood up to the task defensively until Ratuva came in off his wing to charge over. Antonio Rizzi avoided being penalised for obstruction on the TMO review and Allan held his nerve to land the all-important conversion.