The English premiership leaders made it 11 victories from 11 attempts this season to spoil Connacht's Heineken Cup debut at the Twickenham Stoop.

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 25-17 triumph in Pool 6.

The reigning Amlin Challenge Cup Champions needed two late penalties from the reliable boot of Nick Evans to finally end Connacht's dogged defiance in south west London.

Evans struck his sixth and seventh successful kicks at goal in the 77th and 79th minutes to hand Quins a valuable four match points after Conor O'Shea's side had been outscored by two tries to one.

Evans kicked Quins 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 the 22 created a two-on-one for the visitors, with Tiernan O'Halloran on hand to claim Connacht's opening Heineken Cup try.

Miah Nikora added the conversion to his seventh-minute penalty and Connacht were 10-6 to the good as the game reached the quarter-of-an-hour mark.

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 a well-taken try from halfback partner Karl Dickson with 31 minutes gone. The former Bedford Blues No9 burrowed over from close range after Jordan Turner Hall had twice been involved in a patient build up.

Evans completed the seven-point score from wide on the left as he made amends for a penalty miss 10 minutes earlier.

The Kiwi fly-half then ensured the hosts finished the half two scores clear 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 period, they were left disappointed, with Connacht ensuring the final 40 minutes were an even tighter affair as they worked their way back to within touching distance of a famous success.

Quins prop and Heineken Man of the Match Joe Marler saw a try ruled out for a truck and trailer offence on 49 minutes before Gavin Duffy narrowed the gap with a fine score for Connacht. The Ireland 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 Quins faithful 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.