Harlequins opened their 2011/12 Heineken Cup account with a close 25-17 win over tournament newcomers Connacht at the Stoop on Friday.
The hosts took their impressive domestic form on to the European stage as they began their European Cup campaign with yet another win, although this one was in the balance until the final whistle.
The Aviva Premiership leaders made it 11 victories from 11 attempts this season to spoil Connacht's Heineken Cup debut.
The Irish province gave a hugely positive account of themselves after stepping up to the big time following 15 years in the Amlin Challenge Cup but Quins did just enough to secure a hard-fought triumph in Pool 6.
Connacht outscored their hosts by two tries to one, and the reigning Amlin Challenge Cup champions needed two late penalties from the reliable boot of Nick Evans to finally end Connacht's dogged defiance.
Evans struck his sixth and seventh successful kicks at goal in the 77th and 79th minutes respectively to hand his team a valuable victory, denying Connacht a losing bonus point in the process.
Evans kicked Harlequins into a 6-3 led before the game was 10 minutes old but it was Connacht who struck first as far as tries were concerned.
Eoin Griffith's inside step on the edge of Harlequins' 22 created an overlap for the visitors, and winger Tiernan O'Halloran was on hand to claim Connacht's opening Heineken Cup try.
Pivot Miah Nikora added the conversion to his seventh-minute penalty and Connacht held a surprising 10-6 lead after a quarter of the match played.
Eric Elwood's men enjoyed plenty of possession and a fair share of territory for the remainder of the half but Quins were the only team to add to their tally before the break.
A third penalty from Evans was followed by 13 phases from Quins and a well-taken try from Karl Dickson in the 31st minute, after the scrum-half burrowed his way over from close range.
Evans added the extras from out wide as he made amends for a missed penalty a few minutes earlier.
The former All Black pivot then ensured the hosts finished the half two scores clear (19-10) as Connacht were punished for a high tackle on the ever-industrious Chris Robshaw.
If the Quins faithful expected their side to run away with things in the second half, they were left disappointed as Connacht ensured the final 40 minutes were an even tighter affair after working their way back to within touching distance of a famous success.
Connacht captain Gavin Duffy narrowed the gap with a fine score for his team after the former Quins full-back marked another return to his old stomping ground with a 25-metre sprint to the line following a superb cut-out pass from replacement fly-half Niall O'Connor.
O'Connor calmly slotted the extras to make it a two-point ball game and create an unwanted nervy final quarter as far as the local supporters were concerned.
But just as the smell of an upset began to surround the Stoop, Evans produced his usual heroics to mark his team's 50th Heineken Cup appearance with what could prove to their most important win of the term so far.
Pens: Evans 6
Tries: Duffy, O'Halloran
Cons: O'Connor, Nikora
Harlequins: 15 Mike Brown, 14 Seb Stegmann, 13 George Lowe, 12 Jordan Turner-Hall, 11 Sam Smith, 10 Nick Evans, 9 Karl Dickson, 8 Nick Easter, 7 Chris Robshaw, 6 Maurie Faasavalu, 5 George Robson, 4 Ollie Kohn, 3 James Johnston, 2 Chris Brooker, 1 Joe Marler.
Replacements: 16 Joe Gray, 17 Nic Mayhew, 18 Kyle Sinckler, 19 Tomas Vallejos, 20 Luke Wallace, 21 Danny Care, 22 Benjamin Urdapilleta, 23 Tom Williams.
Connacht: 15 Gavin Duffy, 14 Brian Tuohy, 13 Eoin Griffin, 12 Dave McSharry, 11 Tiernan O'Halloran, 10 Miah Nikora, 9 Paul O'Donohoe, 8 George Naoupu, 7 Ray Ofisa, 6 John Muldoon, 5 Mike McCarthy, 4 Michael Swift, 3 Rodney Ah You, 2 Adrian Flavin, 1 Brett Wilkinson.
Replacements: 16 Ethienne Reynecke, 17 Ronan Loughney, 18 Dylan Rogers, 19 Dave Gannon, 20 TJ Anderson, 21 Frank Murphy, 22 Niall O'Connor, 23 Henry Fa'afili.
Referee: Jérôme Garces