To compound matters for Wales, they will be missing several top players on Saturday when they face the renowned physical power of the Springboks.
British & Irish Lions Gavin Henson, Tom Shanklin, Gethin Jenkins and Ryan Jones are already sidelined, while Brent Cockbain is unlikely to play again this season because of a hamstring injury that requires surgery, and scrum-half Dwayne Peel is also racing against the clock.
Coach Mike Ruddock has called up five players to train with the squad this week - Daffyd James, Andy Williams, Ben Broster, Ian Evans and Andy Powell - as injuries have taken a hefty toll.
But Thomas, who was given leave from the Fiji game to play for his club Toulouse in a French Championship match, is eagerly awaiting a backs-to-the-wall battle that lies ahead.
"I am not going to make excuses regarding injury or lack of preparation, because that is all it is - excuses," he said.
"You come here, you are playing for your national team, you should be good enough to be here, and as long as you give your all you can't ask for any more.
"We have got to get totally stuck in, it is a massive week for us, and this is the kind of thing that I love about international rugby, especially being captain, the fact that now we will be written off.
"There is no better thing in sport, as far as I am concerned - to show your character when everyone writes you off and puts you in a corner.
"It is up to you to fight your way out of it, and I believe as a team it is about showing your character, both as a rugby player and as a person."