Wasps weathered a stirring second-half fightback from London Irish at the Causeway Stadium on Sunday to clinch only their third victory of the Zurich Premiership season.

The Wycombe-based club were coasting towards the end of the half thanks to the boot of Kiwi fly-half Mark van Gisbergen and a well-worked try from Shane Roiser who crossed in the 25th minute as the home side racked up a 16-3 interval lead.

But the Exiles hit back through Mark Mapletoft who rifled over four unanswered penalties to drag Irish back into the game, only for Van Gisbergen to slot six more points in the last 10 minutes to seal the victory.

Irish earned a bonus point to give them some reward for a brave performance but it could have been a different result had they made the most of several promising field positions and they were frequently guilty of taking the wrong option.

They failed to register a try but there was still plenty of invention in their play as they went in search of a third consecutive Premiership triumph and English champions Wasps were made to work for their four-point haul.

It was not a classic however - a fact that quickly became apparent following a sloppy opening 10 minutes which saw Van Gisbergen slot an easy penalty.

But the game burst into life shortly after when flanker Phil Murphy broke up the centre of the pitch - he was eventually collared but managed to offload the ball which was spun to Ed Thrower via Justin Bishop, only for the full-back to knock on as he was tackled over the line.

They were not left empty-handed however as Mapletoft was presented with a simple shot at goal, after Wasps infringed, which the in-form fly-half gratefully accepted - in contrast to Van Gisbergen who had missed two further penalties.

Wasps extended their lead against the run of play through Roiser, who accepted Fraser Waters' inside pass after Rob Howley had charged down an Exiles clearance and strolled home under the posts.

Van Gisbergen made no mistake with the extras and then booted his second penalty as Wasps kept the scoreboard ticking over, although there was still very little to choose between the two teams.

Warren Gatland's men started to take the initiative as the first half neared its conclusion however and went close in the 40th minute only for Waters' pass to fly into touch with an unmarked Roiser waiting.

Irish's defence looked solid enough but they were powerless to prevent Van Gisbergen's third penalty as Wasps - with Samoan winger Trevor Leota prominent in the loose - turned the screw.

But the Exiles hit back early in the second half as Mapletoft slashed the deficit to just four points with three penalties in quick succession as Irish began to attack with increasing regularity - the pace of Thrower proving particularly menacing.

Both teams created chances - Darren Edwards was culpable of taking the wrong option for the visitors while Wasps' Tom Voyce was only kept out by a magnificent try-saving tackle from Paul Sackey - and the game was evenly poised.

Mapletoft was on target once again but replacement Rob Hoadley was sin-binned with four minutes to go and Van Gisbergen cannoned over the resulting place kick before adding his fifth in injury time as the Exiles' hopes faded.