DAN SHEEHAN scored a second-half hat-trick of tries as Leinster dented Ulster’s URC play-off hopes at the Aviva Stadium. The Ireland hooker’s treble helped Leo Cullen’s side bound nine points clear at the top but last night’s visitors are tenth, two places outside the play-off spots with three rounds of regular-season games remaining. A much-changed Leinster forced a late penalty try to lead 19-10 at half-time after Tommy O’Brien and Thomas Clarkson had both crossed over. The second half brought Sheehan’s treble as well as one for his Ireland team-mate Garry Ringrose. Despite Sheehan’s hat-trick, speedy winger O’Brien was player of the match and he reckoned the win was not as straightforward as the final scoreline suggested. He told Leinster TV: “It was a crazy, physical game but I was delighted to stay in it and get a great win. I’ve had a run of games now and I’m really enjoying my rugby at the moment.” As well as his own try, O’Brien set up one of Sheehan’s with a brilliant kick and added: “I preferred the assist — my kicking game doesn’t get any credit so I’ll take that one.” Despite Ireland centre Stuart McCloskey’s late withdrawal, Ulster started positively with Jack Murphy kicking them in front in the eighth minute. O’Brien opened Leinster’s account in the 19th minute when he won the race to his own chip kick, beating Nathan Doak to ground the ball. Injuries to Stewart Moore and Michael Lowry led to more back-line disruption for Ulster, who were operating with a six-two bench split. Despite some lineout struggles for Leinster, the Ulster defence was worn down for Clarkson to burrow over. Ciarán Frawley’s conversion made it 12-3 but Ireland lock Cormac Izuchukwu, who stole a number of Leinster’s lineouts, took a great line on to John Cooney’s inside pass to weave his way over for Ulster and Murphy added the extras. However, No 8 Dave McCann collapsed a Leinster maul to concede the penalty try and earn a yellow card. A rapid start to the second half saw Ringrose cross to secure the league leaders’ bonus point. Tom Stewart’s dummy lineout throw let Leinster off the hook after Diarmuid Mangan had seen yellow for lifting a rival player’s legs above the horizontal. Richie Murphy’s men fell further behind when O’Brien broke on to a Frawley dink forward and superbly picked out Sheehan (inset) on the right to score. Sam Prendergast then played in Sheehan for his second try.Matthew Dalton drove over at the other end, only for Fintan Gunne to send Sheehan charging over in the left corner to complete his hat-trick.  SCORERS — Leinster: Tries, O’Brien, Clarkson, Ringrose, Sheehan 3, penalty try; cons, Frawley, Prendergast. Ulster: Tries, Izuchukwu, Dalton; cons, Murphy 2; pen, Murphy