Worcester Warriors centre Ryan Mills has stressed the importance of staying disciplined in Friday's Championship play-off semi-final second leg after five yellow cards in two matches.
Warriors take a narrow five-point lead into the return game with London Scottish at Sixways.
But boss Dean Ryan has warned his team over their "responsibilities".
"We need to keep everyone on the pitch if we're to get through," Mills told BBC Hereford & Worcester.
"We've had five yellow cards in two games and that makes a massive difference. You can't keep playing with 14 men for as long as we have against the opposition we have been.
"We've worked nine months towards this and motivation levels are though the roof, but ramp it up too much and you can lose a lot of discipline, which has happened the past two weeks.
"We've had a couple of silly yellow cards we've been disappointed with, but a couple have come from sustained pressure from the opposition. We need to keep a lid on our emotions but still have enough to carry us through. It's quite a tough balance."
|Dean Ryan on Worcester's injury situation|
|Chris Pennell (knee) - "He's having rehab on his knee from the injury from the Bristol game and won't be available this week"|
|Charlie Mulchrone (ankle) - "He's seeing a specialist this week. We won't know until he's seen the specialist."|
|Andy Symons (head) - Back in contention, having missed two weeks after being treated for concussion.|
|Max Stelling (hamstring) - "He's having rehab to see when we can get him back. He won't be available for Friday."|
The yellow cards for All Blacks winger Cooper Vuna and former Wales international Jonathan Thomas proved a big factor in Warriors' 30-26 home defeat by Bristol, the game that cost them top spot in the final Championship table.
Thomas's came at a double cost, as it was his third yellow card of the season, ruling him out of the play-off first leg against Scottish.
"Players need to understand their responsibilities and the impact it has at this time of year," added director of rugby Ryan.
"It's influencing our chances of getting through. We've got to get that right this week. Three yellow cards in a game is unacceptable. We have an ongoing relationship with the RFU refereeing department. We're having regular meetings to address a theme which is not working in our favour."
Although he has Thomas back from suspension and centre Andy Symons is available again following concussion, Ryan is again without England full-back Chris Pennell (knee) and centre Max Stelling (hamstring) - and he has a doubt over scrum-half Charlie Mulchrone (ankle).
Added to which, fellow scrum-half Jonny Arr must appear before an RFU disciplinary panel on Wednesday evening (6 May, 18:30 BST) charged with committing a tip tackle in Saturday's victory in London.
"We've got some injury concerns," added Ryan. "But we're working hard to get everyone through."