Harlequins, with 14 successive wins in all competitions this season, tackle four-time champions Toulouse on Friday on a European Cup weekend where the top two sides in each of the six pools clash. Harlequins, the English Premiership leaders, welcome the French Top 14 pace-setters to the Twickenham Stoop, in the first of a double-header which should go a long way in shaping the quarter-final line-up. The two sides have eight points from their opening two matches and are locked at the top of Pool Six. Quins were European Challenge Cup winners last season and a win over Toulouse on Friday would make it 11 straight wins in the two European club tournaments. The English side are hopeful that injured No 8 Nick Easter, who missed last week's domestic win over Wasps, will be fit to return. "Toulouse are the big guns and it's a big test for us. No wonder the game is already a sell-out," said captain Chris Robshaw. The French side will be looking to former All Black fly-half Luke McAlister and Wallabies scrum-half Luke Burgess to orchestrate the breakthroughs. "I know that Harlequins are a great team," said 28-year-old Burgess. "They are very physical and skilful - especially Danny Care, an extremely talented back. "However, they also have players like Nick Evans and Nick Easter so all in all they are a very challenging squad to play against." Toulouse will be without experienced full-back Clement Poitrenaud who suffered a serious left ankle injury in last weekend's 33-12 Top 14 win over Toulon and will not play again this year. It is the same injury he picked up in 2008 which required surgery. Defending champions Leinster, who lead Pool Three on seven points after defeating Glasgow but drawing with Montpellier, travel to second-placed Bath, the 1998 champions. Bath lost to Glasgow Warriors before sneaking past Montpellier 16-13. "If you don't win your home games you will be on the way out of the tournament - and you need to get at least a losing bonus point away from home as well," said Bath scrum-half Michael Claassens. Bath are without flanker Lewis Moody, who is out of action for 10 to 12 weeks after undergoing shoulder surgery. But they will have flanker Francois Louw and fly-half Stephen Donald available for Sunday's game. Pool One leaders Scarlets face former two-time winners Munster with the Irish side without former All Black flyer Doug Howlett who will miss the rest of the season after rupturing his Achilles in last weekend's Celtic League defeat to Ospreys. In Pool Two, Edinburgh face second-placed Cardiff in the Welsh capital, having collected nine points from wins over Racing-Metro and London Irish. They will be buoyed by the knowledge that Cardiff will be without experienced flanker Martyn Williams. The 36-year-old former Welsh international has already been out for three months with a broken arm and has now suffered a recurrence of the problem in training. Pool Four sees 2001 and 2002 champions Leicester go to Clermont with the Tigers two points clear at the top after wins over Aironi and Ulster. English Premiership champions Saracens and Ospreys face off in Pool Five at Wembley with the Welsh side featuring winger Shane Williams, who played his last international against Australia last Saturday. Saracens played at Wembley last season but went down to a 25-23 defeat against Leinster.