While Quins march on towards potentially pivotal Pool Six home and away encounters against four-time European champions Toulouse next month after this 28-9 success, Gloucester face making an early exit following two defeats in a row.
First-half tries by full-back Mike Brown and centre Matt Hopper put Quins in charge, but once again it was goalkicker Nick Evans who underpinned victory as he booted three penalties and two conversions.
Quins' England number eight Nick Easter completed an emphatic away success when he touched down eight minutes from time, inflicting a heaviest Heineken home defeat on Gloucester since Stade Francais demolished them 27-0 at Kingsholm six years ago.
In the group's other match, Lionel Beauxis kicked 21 points for Toulouse as Connacht were beaten 36-10 by thoroughly professional opponents side in their first ever home match in the competition.
Heineken Cup debutant Matthew Morgan salvaged a 26-26 draw for the Ospreys against Treviso in Pool Five with a dramatic last-minute penalty at the Stadio di Monigo.
Trailing in the dying moments, the Welsh region looked set to suffer one of the greatest European upsets of all time.
However, with just seconds remaining, 19-year-old Morgan cracked over a stunning penalty from 40 metres to break Italian hearts and earn Sean Holley's men a draw which they scarcely deserved.
Tobias Botes, Benjamin De Jager and Michele Rizzo scored the Italian side's tries, while Ryan Jones and Tommy Bowe crossed for the Ospreys.
Elsewhere in that group, Saracens salvaged a losing-bonus point at the death as Biarritz edged out the English champions 15-10 in a ferocious encounter.
An attritional first half ended scoreless after Owen Farrell and Marcelo Bosch squandered several shots at goal.
Biarritz came to life in the second half and scored through Imanol Harinordoquy and Takudzwa Ngwenya to seal the victory.
But to the delight of the Saracens coaching staff, Alex Goode squeezed into the corner with the last play of the match to earn a bonus point.
It was a case of deja vu in the south of France as Ronan O'Gara struck a dramatic drop goal at the death to see Munster overcome Castres 27-24 in Pool One.
In a frenetic, error-strewn encounter in Toulouse, tries from hooker Brice Mach and replacement winger Pierre Gilles Lakafia, either side of a Doug Howlett try for the visitors, gave Castres an 18-10 half-time lead.
Peter O'Mahony's early try in the second half gave Munster hope, however, and Will Chambers put them in front 14 minutes from time after O'Gara charged down Remi Tales' attempted clearance kick.
Pierre Bernard levelled things with a penalty only for O'Gara, just as he did against Northampton, to snatch a narrow victory with the last kick of the game.
Matt Smith scored the only try late on as Leicester beat Ulster 20-9 to top Pool Four.
Leicester's Toby Flood and Ulster's Ian Humphreys dominated most of the game with their kicking but the Tigers eventually pulled away to win.
Northampton did nothing to enhance Jim Mallinder's case to be the next England manager as they crashed to a second consecutive defeat, beaten 28-23 by Scarlets on Friday night.
Mallinder is widely regarded as the leading domestic candidate to replace Martin Johnson, having guided the Saints from the second division to last season's Heineken Cup final in three years.
But his reputation suffered an untimely dent as Northampton, who lost in agonising fashion at Munster last weekend, were beaten at home.
The Saints would rightly question some of the refereeing decisions but the Scarlets capitalised on an error-strewn performance to move clear at the top of Pool One with a bonus-point victory.
The Scarlets, who opened their campaign with victory over Castres, had the game wrapped up by half-time with tries from Liam Williams, Aaron Shingler and Matt Gilbert.
Rhys Priestland, the Wales fly-half making his first start since the World Cup, scored the bonus-point try as the Scarlets counter-attacked following a Chris Ashton knock-on.
The Saints staged a late comeback to earn a losing bonus point with tries from George Pisi and Tom Wood, on top of 13 points from Ryan Lamb.
Elsewhere, fly-half Dan Parks kicked 14 points as Cardiff Blues made it two wins from two in the Heineken Cup with a scrappy 24-18 win over 14-man London Irish at Cardiff City Stadium.
First-half tries from hooker Rhys Thomas and scrum-half Lloyd Williams laid the groundwork for an 18-9 half-time lead for the hosts, by which time the visitors were a man down after centre Steven Shingler saw red for a reckless spear tackle on opposite number Dafydd Hewitt.
Parks' boot eventually sealed the hosts' win with two second-half penalties but Irish refused to buckle and bravely kept themselves in the game through the boot of full-back Tom Homer, who kicked all their points to earn what could yet prove to be a valuable losing bonus point.
In the other Pool Two game, Tim Visser's try double earned Edinburgh a sensational 48-47 success over Racing Metro at Murrayfield.
The 'Flying Dutchman', who will qualify to play for Scotland at the end of the season, scored a try after 35 seconds and another four minutes from time as Edinburgh sensationally came from behind to triumph and claim a second win from two games following last weekend's win at London Irish.
The hosts scored 17 points in the opening 10 minutes but conceded 28 unanswered points and were trailing by 20 with 14 minutes remaining.
But Racing replacement Jone Qovu was sin-binned with 11 minutes to go and Edinburgh scored two converted tries to triumph, with captain Greig Laidlaw kicking the winning conversion.
Edinburgh's tries came from Visser (two), Netani Talei, Tom Brown, Roddy Grant and Laidlaw, who added six conversions and two penalties in a 23-point haul.
Racing finished with five tries - for Julien Saubade, Juan Imhoff, Henry Chavancy (two) and Jonathan Wisniewski, who kicked 20 points, while Juan Martin Hernandez kicked one conversion but missed a drop-goal attempt with the last play of the game.
Clermont Auvergne picked up their first win of this season's competition in some style as they put Aironi to the sword 54-3 in a one-sided clash at Stade Marcel Michelin.
The star-studded French side had lost their opening Pool 4 clash to Ulster but they bounced back with an eight-try mauling of Aironi, with Lee Byrne, Gerhard Vosloo and Brock James going over in the first half and Julien Bonnaire, Julien Bardy, Jean-Marcel Buttin, Wesley Fofana, and Julien Malzieu adding second-half scores.
Scrum-half Morgan Parra converted four of those tries, while fly-half James successfully added the points for the three of the others.
Italian side Aironi, who lost their first match to Leicester, managed only an early Luciano Orquera penalty in reply.
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