Brian O’Driscoll scored a hat-trick of tries as Leinster climbed back to the top of Pool 2 with a hard-fought bonus-point win over Agen in Dublin.

The last game at Lansdowne Road before the famous ground’s revamp ended with a home victory, but there were plenty of nervous moments for Irish fans and many of them won’t be looking forward to next weekend’s return match at Stade Armandie.

With star fly-half Felipe Contepomi out injured, Leinster’s goal-kicking duties were handed to full-back Girvan Dempsey – probably for the last time. Dempsey missed his first three attempts at goal by some distance, and it could have cost side dearly.

Leinster stunned the visitors with a third-minute try to Australian scrum-half Chris Whitaker, and the Lansdowne Road crowd were on their feet moments later when their hero O’Driscoll snapped up a loose pass and raced 90 yards to beat a rapidly closing Rupeni Caucaunibuca to the try-line.

O’Driscoll should have had a second, but was denied by a superb tackle from Fijian star Caucaunibuca and Leinster were probably lucky to go into the break leading a tough Agen side 10-3.

After Dempsey’s third miss, centre Gordon D’Arcy took over the responsibility and his first effort – albeit from point-blank range – gave the home side a 10-point buffer.

Leinster repelled several Agen attacks before a blatant foot-trip from fly-half Jerome Miquel gave D’Arcy another three points, and an O’Driscoll try from 90 inches, rather than yards, looked to have ended the French club’s resistance.

Lethal try-scorer Caucaunibuca kept the visitors in touch with a good score, but a yellow card to Agen’s New Zealand prop Kees Meeuws and O’Driscoll’s third ended their faint hopes of a comeback.