The Amlin Challenge Cup continues this weekend with Aviva Premiership clubs Bath, Wasps, Newcastle Falcons and London Irish all in action.
Pool 2 leaders Bath are in Italy on Saturday to take on Mogliano, who have lost both of their pool matches so far.
Head coach Gary Gold has rung the changes, with Nathan Catt and Dominic Day the only two in the starting line-up who also started against Exeter Chiefs last weekend.
Catt is joined in the front row by Argentina internationals Eusebio Guinazu and Juan Pablo Orlandi, whilst Day is partnered at lock by Ryan Caldwell. An all-new back row of Will Skuse, Mat Gilbert and Carl Fearns completes the pack.
Micky Young makes his return from injury to partner Tom Heathcote in the half-backs, with Olly Woodburn and Richard Lane continuing their comebacks out wide on the wings.
Gavin Henson has also recovered from injury to link up with Kyle Eastmond in the centres. Nick Abendanon captains the side from full-back.
Wasps, like Bath, have a 100 per cent record from their two pool matches ahead of Saturday's clash against French outfit Grenoble in Pool 4.
The Premiership side have also made changes. The Londoners have made four from the side that beat London Irish 19-12 last weekend.
Up front, Tom Palmer is given the nod in the second row, partnering Joe Launchbury, with Kearnan Myall moving to the bench.
It is all change for the halfbacks, with Joe Simpson and Joe Carlisle starting in the places of Charlie Davies and Andy Goode, who both picked up knocks last weekend.
"I have always highlighted the importance of this period either side of Christmas in influencing what direction your season can take and these back to back games against Grenoble could, to a great extent, determine the success of our European campaign," said director of rugby Dai Young.
Elsewhere, Bucuresti take on Brive in Pool 3 while Cavalieri Prato do battle with Lusitanos in Pool 5.
On Sunday Newcastle Falcons will give youth a chance against Cammi Rugby Calvisano at Kingston Park.
No fewer than 12 new faces come into the side with a mixture of youth and experience getting the chance to shine on the European pedestal. Seven of the starting XV are the products of the Falcons academy.
"Calvisano are a side that have nothing to lose, and will be a tough proposition for the lads," said Newcastle's Dean Richards. "We will blood a lot of these boys over the next couple of weeks with a view to perhaps using them during the Premiership as well because most of them are that good."
Shane Geraghty will captain London Irish against the mighty Stade Francais in Pool 5 at Madejski Stadium.
The fly-half will be partnered by Darren Allinson at half-back with Guy Armitage and Fergus Mulchrone in the centre. Andrew Fenby, Tom Fowlie and Alex Lewington will make up the back three.
John Yapp, Jimmy Stevens and Leo Halavatau will start in the front row with Nic Rouse and Bryn Evans forming a new second row combination. Kieran Low, who recently made his Scotland debut, Jebb Sinclair and Chris Hala'ufia make up the back row.
Brian Smith, Exiles director of rugby said: "We've a lot to play for as a group - we currently sit at the top of the pool and we'd like to stay there. Whilst we're using the Amlin Challenge Cup to develop youngsters like Tom Fowlie we still want to win. It's a big challenge against one of the giants of French rugby but we're up for the fight."