Discipline will be key to Leeds Carnegie's victory hopes

Andy Key has urged Leeds Carnegie not to pay the penalty in their teak-tough Amlin Challenge Cup examination at big guns Stade Francais tomorrow (5.45pm).

It's comfortably Carnegie's most onerous Pool Four test and the outcome of it will go a long way towards deciding who qualifies for the knock-

out stages, with the Parisiens firmly in the box seat.

* Click here to watch the latest edition of our rugby union programme The Line Out.

Stade currently top the pool with 19 points following four successive victories, five points clear of Carnegie, who ideally need to beat their decorated French hosts tomorrow and claim a try bonus, while denying their rivals a losing bonus point.

It's a huge ask for Carnegie, who host Bucuresti in their final pool assignment a week tomorrow, with Stade expected to make light work of final-day opponents – group whipping boys Crociati.

And it's made even more daunting by the fact that Stade looked the real deal in last weekend's sensational 31-3 French Top 14 slaying of Toulouse, although it remains to be seen whether the make-up of their line XV is much changed tomorrow with the Six Nations beckoning.

The likes of England's James Haskell and French wrecking-ball centre Mathieu Basstareaud - who both scored tries against Toulouse - both sat out Stade's fortuitous 22-13 victory in Leeds, as did Italy skipper Sergio Parisse and Scotland's Hugo Southwell.

But it's fair to say whatever side Stade field will ask plenty of questions of Carnegie, with the game to be played at Paris' Charlety Stadium.

Director of rugby Key said: "Our discipline is going to be huge in this game.

"Discipline, not in just giving penalties away, but in terms of organisation because sides like Stade have unbelievable flair who can hurt you massively, if you give them some ball.

"We know they are going to have it and our defence at the weekend (at Bath) was awesome, like it was the weekend before.

"If we can improve even another five per cent on our defence as we're looking for, then we know we are going to deprive them of opportunities.

"That's an important thing against sides like Stade. You can't give

them opportunities to use the ball as they have too much flair."

Aussie close-season recruit Lachlan Mackay will not be risked after suffering a groin strain at Bath, which is set to rule him out until next week.

Wing Michael Stephenson also misses out after suffering a dead leg against his former side last weekend.

Meanwhile, Key is backing playmaker Mackay – who probably would have played if tomorrow's game had been in the Aviva Premiership – to be an instrumental force for Carnegie between now and season's end.

The marquee close-season recruit did it tough on the sidelines in the first half of the campaign with a shoulder problem, but finally hit his straps on New Year's Day after being switched to fly-half in Carnegie's priceless home victory over Gloucester – their first in the top-flight this term.

The bold decision to move Mackay from to the key position of 'ten' proved a masterstroke and Key insists he and head coach Neil Back always envisaged playing the former Australia international in the pivotal role when the need arose.

Key said: "Lachlan was always going to be somebody who we felt, along with Scott Barrow, who would be an important player this season who would not only demonstrate how important they were, but also bring an influence to the team. People saw that last weekend, with the way we controlled the game.

"There was no surprise from what happened at the weekend. That's what we brought Lachlan in for when we were going through the players we needed to bring in.

"We always had that balance between what we could spend and get for our pound - in terms of doubling up players who had the ability to play in different positions.

"Earlier in the season, we had Michael Stephenson playing at full-back rather than wing. We knew Lachlan had not played a lot of ten at Brive, but had a lot back in Australia. We knew when he came to us we'd got an accomplished ten and 12 (inside centre), which would give us better flexibility."