Oswin Appollis netted the opener for South Africa after 21 minutes, but they were pegged back soon after as Show deservedly equalised for the Angolans following a sustained spell of pressure.
It took a late winner from Lyle Foster to secure all three points, but Broos was unhappy that his side could not kill the game off sooner.
“As I said before the game, losing your first match puts you in difficulty,” he said. “We tried to avoid that and we started the match very well. We played well, we scored, and then, for reasons I don’t understand, suddenly we fell asleep.
“Angola came into the game and were dangerous with their combinations, and we suffered. There was no aggression anymore, no passion in the team, and we played very slowly. You could feel there would be a goal for the opponent, and that happened.”
Broos replaced winger Mohau Nkota with Tshepang Moremi at halftime, a change that immediately gave Bafana Bafana a lift as they seized control of the match again.
“We needed to find our usual game and we put some things right at halftime. Moremi played well, was quick and a threat to the Angolan defence. That changed a lot.
“We were also more aggressive and put more pressure on the opponent. We scored through Moremi – OK, it was offside – and then there was the shot from (Mbekezeli) Mbokazi that hit the crossbar.
“But a fantastic goal from Lyle made us very happy with the victory. Now we can look ahead to the game against Egypt on Friday in very different circumstances than if we had lost today.”
Broos admitted their first-half slump was a wake-up call for the team, but predicted it would be a one-off at the tournament.
“We have to play like we did in the second half going forward. The first half, I don’t know why, but it was not the South Africa I am used to seeing. There was no depth in our team and we gave the opponent the chance to put pressure on us.
“But maybe it was good that it happened, because we got a wake-up call in the first 45 minutes. I don’t think it will happen again.”
As for how far Bafana Bafana can go in the tournament, Broos believes that if they play to their usual level, anything is possible.
“This is a tough tournament and sometimes you need a little bit of luck. We will see what we can do. I am confident because I saw in the second half what I want to see – the passion and the aggression,” he said.