English champions Harlequins kick off their Heineken Cup campaign against Biarritz at the Stoop on Saturday.
The 2011 Amlin Challenge Cup winners host the two-time Heineken Cup Finalists and reigning Challenge Cup champions arguably the most important clash in Pool 3.
Harlequins failed to reach the knock-out stages in last season's Heineken Cup despite beating four-time winners Toulouse away from home as they stumbled at the last hurdle against Connacht (with whom have have been drawn again) on the lsat day of the pool stages.
Harlequins have never faced Biarritz in the tournament but skipper Chris Robshaw is well aware of the importance to get off to a winning start.
"We want to push through to that quarter-final stage. It's all about winning your first couple of games. As soon as you let those slip away you're playing catch-up," he told the ERC website.
Biarritz made a flying start to the Top 14 season but have lost their last four games.
Bairritz have named former Crusaders and Leinster playmaker Mat Berquist at fly-half while ex-England full-back Iain Balshaw also starts.
French internationals Imanol Harinordoquy and Dimitri Yachvili are absent due to injury while Damien Traille is on the bench.
There are five changes to the Harlequins team that started against Exeter Chiefs last weekend.
Tom Williams has recovered from a hip injury and starts on the right wing, while Danny Care returns at scrum-half.
Among the forwards Joe Marler comes in at loose head, with Rob Buchanan making his first start of the season at hooker where he replaces Joe Gray, who is having treatment to an injury which will prevent him playing for a number of weeks. Gray's injury status will be updated following a specialist's opinion.
Maurie Fa'asavalu returns to the starting line-up with captain Chris Robshaw and Nick Easter completing the back row.
Among the replacements, Dave Ward will look to make his first senior appearance, while Ben Botica and Seb Stegmann provide cover for the backs.
Heineken Cup betting odds
Harlequins:15 Mike Brown, 14 Tom Williams, 13 Matt Hopper, 12 Jordan Turner-Hall, 11 Ugo Monye, 10 Nick Evans, 9 Danny Care,8 Nick Easter, 7 Chris Robshaw, 6 Maurie Fa'asavalu, 5 George Robson, 4 Ollie Kohn, 3 James Johnston, 2 Rob Buchanan, 1 Joe Marler,
Replacements: 16 Dave Ward, 17 Mark Lambert, 18 Will Collier, 19 Charlie Matthews, 20 Tom Guest, 21 Karl Dickson, 22 Ben Botica, 23 Seb Stegmann,
Biarritz: 15 Iain Balshaw, 14 Taku Ngwenya, 13 Dane Haylett-Petty, 12 SeremaÃ¯a Burotu, 11 Aled Brew, 10 Mat Berquist, 9 Yann Lesgourgues, 8 Talalelei Gray, 7 Wenceslas Lauret, 6 Magnus Lund, 5 Thibault Dubarry, 4 Erik Lund, 3 Francisco Gomez Kodela, 2 Arnaud Heguy, 1 Fabien Barcella
Replacements:16 Benoit August, 17 Lodewicus Blaauw, 18 Thomas Synaeghel, 19 Pelu Taele, 20 Benoit Guyot, 21 Julien Peyrelongue, 22 Damien Traille, 23 BenoÃ®t Baby,
Date: Saturday, October 13
Kick-off: 18:00 BST
Venue: Twickenham Stoop
Referee: George Clancy (Ireland)
Assistant referees: Leo Colgan (Ireland), John Carvill (Ireland)
Television match official: Marshall Kilgore (Ireland)
Timekeeper: Bob Ockenden (England)
Assessor: Fergus Neil (Scotland)
Citing commissioner: Alberto Recaldini (Ireland)