The scrum-half crossed once in either half at the Stade Guy Boniface, with his first coming with the game 26 minutes old and his second following six minutes after the break.

The latter score pushed Irish 17 points in front after Steven Shingler had slotted his second conversion to go with a 13th-minute penalty as the visitors took control on French soil.

Mont de Marsan kept the encounter interesting with a converted try from centre Simon Lucu after 54 minutes but Shingler looked to have put the result beyond doubt when he struck a second penalty 17 minutes later.

Lucu's second try made for a thrilling ending, though, as he crossed again with six minutes still left to play. Jean Baptiste Claverie's conversion brought the hosts to within a single score but Irish held firm to head home with another morale-boosting success following last weekend's shock Aviva Premiership win at Kingsholm.

The result still leaves Irish three points behind Gloucester in Pool 1, with the Cherry and Whites knowing victory at bottom side Bordeaux-Begles tomorrow night will guarantee a place in the last eight and knock their English rivals out in the process.