The defender reminded everyone they have pulled off even bigger miracles.
The man who scored the winner against France at Hampden in 2006, and was part of the squad which won by the same 1-0 scoreline in Paris a year later, reckons winning in Brussels is not as big an ask as either of those achievements. Caldwell, with 52 caps under his belt, has been through too many crises to press the panic button, and insisted: "Winning in Brussels would be a big result in Scotland's history.
"But not the biggest, and I don't think it is impossible. It is do-able.
"We have a good group of players. We just need something to click, whether it be a bit of luck or a bit of quality.
"I am positive that, with the group we have got, we can do that.
"We will certainly try our very best. That's all we can say."
Failure to take three points would have serious ramifications, not just for the national team – who could wave goodbye to any slim hope of qualification for Rio 2014 – but for manager Craig Levein, who could be out of his job by the end of the week.
A fact not lost on Caldwell who is still smarting from the defeat in Cardiff which left Scotland in second-bottom spot in Group A.
"Everyone could say they gave their all against Wales," he reflected.
"But sometimes in football, and sometimes in life, you don't get what you deserve.
"Friday was one of those occasions.
"We gave it everything, and, barring a couple of breaks which went against us, we could have won the game.
"That's what we need to remember as we go into this game. I'm sure one turn of luck could change it completely.
"We believe we can win tonight.
"That's the group of players we have got, albeit the start we have made to the campaign is far from what we wanted.
"We understand that, and we understand we are going to get criticism.
"But, as a group we need to stick together, and come out fighting to win the game.
"The fans deserve no less. They were tremendous in Cardiff."
Caldwell wants to repay them tonight and said: "I've played for Scotland for a long time now and I've never known the fans to question the players or drop their support for us.
"They always come out in their numbers and in great voice, and we don't take that for granted.
"We're bitterly disappointed we have not been winning the games for them.
"All I can say to them is, keep on supporting us because we will keep giving everything we have got to qualify."