Barcelona star Neymar has scored four goals at the FIFA World Cup for the hosts, although he did fail to find the net as Brazil drew 1-1 against Chile in the last 16 before progressing on penalties.
Armero has singled out the 22-year-old as the biggest threat to Colombia's chances of winning the quarter-final clash.
However, full-back Armero is confident of marginalising the talented forward so long as everyone remains focused on their task.
"If we're going to nullify the threat posed by Neymar, then everyone in the team will have to lend a helping hand to the players marking him," Armero told FIFA.com.
"We need to stick together and not lose our focus. We're a compact side, and we know that when we all play for each other we tend to get results."
Colombia may have entered the World Cup as little more than outsiders, but, led by the hugely impressive James Rodriguez, Jose Pekerman's side have emerged as genuine contenders.
And Armero insists that Colombia are not just in the last eight to make up the numbers.
"We are working hard to go as far as we can," he added.
"We knew from the very first game that it wasn't going to be easy, and our approach is to take things one step at a time.
"We haven't come here to enjoy ourselves but to give our all and go for glory."
