Curle's men left it late but sealed all three points courtesy of goals from Jeff Hughes and Francois Zoko in the closing stages.
He said: "The most pleasing thing was Fabian. I just call him Fab. He put in an assured performance, showed good handling, correct decision-making, he was coming for crosses and dealing with things.
"Our back four were comfortable with him behind them and that's the most pleasing thing for me. He got his first professional clean sheet so early in his career."
Curle saw skipper Neal Bishop sent off following an off-the-ball altercation with Pompey captain Johnny Ertl in the final minute.
He played down the incident, but confirmed Bishop will be making a donation to the club's transfer kitty after he picked up a three-match ban.
He said: "The chairman is prepared to dip his hand in his pocket to strengthen the squad and here are the players donating money to the chairman's fund to help us bring in extra players.
"Bish is disappointed. He raised his hand and went to give Johnny Ertl a playful tap to say 'you caught me there with a tackle and you were late'.
"It's not as if he turned around and gave him a right-hander. But for the amount of money he'll have to donate to the football club, he may as well have, although I'm obviously not advocating that."