Stephen Jones fears ruthless Wales head coach Warren Gatland will react to another "unacceptable" display by wielding the axe.
The Grand Slam champions were routed 43-17 by an experimental South Africa side in the opening Test and the necessary soul-searching is well underway.
A ferocious training session this morning overseen by an angry Shaun Edwards has helped sharpen the minds for Saturday's second Test in Pretoria.
Jones - one of the few players to emerge from the ruins at Vodacom Park with his reputation intact - claims another capitulation will lead to casualties.
Wales face South Africa, Canada, New Zealand and Australia in a daunting autumn schedule and Jones believes Gatland will punish those who failed to deliver this summer without hesitation.
"Warren is honest. He spoke to us this morning and made it pretty clear that some things weren't acceptable and that we must raise our standards," said the Scarlets fly-half.
"He's an experienced coach who knows what we've got to do to improve.
"It's not about losing our heads, running around like Tasmanian devils. We need to look at how we can improve things.
"Last weekend was unacceptable. We were unrecognisable from the side we have been this year.
"If we don't front up on Saturday then the coach won't be afraid to make changes.
"We've been made aware that what happened in the first Test in Bloemfontein was unacceptable.
"When you're given the Welsh jersey it's a huge honour, but it's also a huge responsibility.
"If you don't perform you can't expect to be picked the following week."
Wales arrived in South Africa quietly confident they would trouble the world champion Springboks - at least in the first Test.
But instead they were put to the sword, leaving just one more match to atone for a performance that has only hardened opinion the Six Nations sides are soft touches when touring the southern hemisphere.
"I'd like to think we have much more to offer and that's the frustrating thing," said Jones.
"If you come off the pitch having lost yet given your all you'll accept it, but when you haven't contributed like you know you can it hurts.
"The positive side of it is we have Saturday to put it right. We have to come back strongly in the second Test.
"The feeling of pain is there for us all - it's a collective thing. Our performance was not up to standard.
"We were looking forward to the game but we didn't perform. The reasons the players are hurting is because it's a collision sport and we lost the collisions.
"That's the most frustrating thing. We need to be better prepared mentally."