Harlequins revived their Aviva Premiership play-off hopes by dispatching London Irish with the vision of Danny Care inspiring the decisive act of a hard-fought clash at Twickenham Stoop.
England trio Chris Robshaw, Mike Brown and Care returned after being rested for last Saturday's rout by Saracens, but Quins still struggled to dispatch the Exiles.
It was only when Care floated a superb scoring pass to wing Sam Smith in the 70th minute, establishing an 18-9 lead, that Irish were beaten.
Brown, the recently-crowned player of the 2014 RBS 6 Nations, crossed late on to give the scoreline an emphatic appearance that failed to tell the full story of the Exiles' effort.
The boot of full-back James O'Connor, who kicked three penalties, kept them in the hunt until Care spied his chance to deliver the killer blow.
Harlequins had Nick Evans to thank for building their initial lead with the former New Zealand fly-half scoring a solo try and landing two conversions and a penalty.
Quins edged an attritional first half that was light on points, despite the sunshine that greeted the London rivals.
Aside from a lively opening from Irish that saw Topsy Ojo pulled back just short of the whitewash by Smith, both try lines were rarely threatened.
Harlequins-bound wing Marland Yarde almost wriggled through, but Irish's promising start floundered as they conceded penalties at successive scrums.
The whitewash was breached for the only time in the first half when Evans chipped over the visiting defence, jumped to gather the ball and touched down.
Having converted the 12th-minute try, the former All Black then displayed his defensive steel with a thumping tackle on Fergus Mulchrone that flattened the centre.
Irish responded with their brightest spell of the half built around an opportunist counter-attack only for Yarde to scoop the ball into the air as they looked to go wide.
O'Connor and Evans exchanged penalties, but it was the Australian who was on target twice more - once after Tom Fowlie had smashed Matt Hopper into the turf - as Irish took control.
The pressure on Quins continued into the second half, but when O'Connor was offered the chance to kick his side into the lead for the first time, he brushed the right upright.
Yarde and Smith took it in turns to make eye-catching breaks, although the latter should have done more to find his only support runner Care.
The pendulum swung in Quins' favour when Yarde was sin-binned for tackling Jordan Turner-Hall without the ball, enabling Evans to land his second penalty.
The playmaker was enjoying a fine game as he charged down a clearance from O'Connor - the ball bounced safely through the dead ball area - and then raced through the Irish midfield.
Only a tap tackle by Shane Geraghty prevented hooker Dave Ward from crossing as Quins took control of the final quarter.
Irish were beginning to crack under the pressure and the decisive score finally arrived in the 70th minute when Care scooped the ball up from a scrum and floated a missed pass to Smith who dived over.
And with four minutes to go the Exiles' resistance was over as quick hands enabled Brown to slide over the whitewash.