The Betway Premiership club managed to hold the Egyptian giants to a goalless draw at the Cape Town Stadium last week, denying them the advantage of an away goal.
Barker credited the team's resolute defending in both legs, including the return fixture at Cairo International Stadium on Wednesday, where Stellenbosch secured a 1-0 victory to book their place in the last four.
"Yes, I think it was very important for us not to concede in our home game. As you all know, Zamalek had a big chance in the 86th minute, but we made a crucial save. That was a turning point - if they had scored, it would have made things a lot more difficult for us coming here," said Barker.
"So, knowing we hadn't conceded an away goal gave us confidence. The message to the players was simple: we have to show hunger, desire, and put in the work. You don't come to a stadium like this, against the defending champions, and win without giving everything.
Barker praised his players for their effort and commitment, highlighting the sacrifices they made to reach this stage of the competition.
"We knew we'd have to make sacrifices, and credit must go to the players for the work they put in, the discipline they maintained, and their unwavering unity throughout both legs," he added.
Stellenbosch FC's historic run continues, and with one more step to the final, the dream of lifting a continental trophy remains alive.