That's just fear mate
Angola are not used to big games. Portugal are. Angola only got through to the qualifying section with a narrow away goals victory over the mighty Chad. Portugal are used to major games, and only drew 3 of their qualifying games, all away from home. They scored 35 goals including a 7-1 thrashing of Russia, and conceded only 5. Whereas Angola scored 12 goals in 10 games.
I may even be bold and back a ht/ft portugal victory.
Most importantly, this is Portugal's easiest game of the group. They have a decent manager, and a world-class player in Ronaldo. He will destroy Angola by himself.
If I was a bookmaker I'd be offering 1.1 odds. If Portugal don't win this game I'll be extremely surprised to say the least.