Andy Awford praised his Portsmouth team for hanging on when they were under pressure as they beat Oxford United 1-0 at the Kassam Stadium with a late winner from Craig Westcarr.
Unbeaten Pompey have now won three of their first four games, but former boss Michael Appleton is still looking for his first point at Oxford, who have slipped to the bottom of Sky Bet League Two.
Westcarr pounced in the 80th minute when he prodded home a high loose ball after the U's defence and goalkeeper George Long failed to deal with a cross from the left from Nicky Shorey.
Portsmouth did well to stay in the game without conceding in the first 45 minutes, when Oxford dominated possession.
But Awford said he got his message across during the interval, and his team were much better in the second half.
"In the first half we didn't play at our best, we were camped in a bit, but the important thing when that happens is to hang in there, and we did that," Awford said.
"It was a really hard-earned three points.
"The half-time message was to keep the ball better. In the second half we were a lot better and controlled the game.
"It wasn't the prettiest of goals but Craig Westcarr won't mind that. That's two goals in two games for him now and he's full of confidence.
"The keeper did well for us with one really good save, but they were all superb. This is not an easy place to come."
Oxford were left to rue some poor finishing, and ill fortune, as for the second successive game Danny Hylton appeared to be tripped inside the box, but was not rewarded with a penalty.
U's manager Appleton said: "We again created enough chances to have won the game.
"When you're on top in games, as we clearly were in the first half, you have to make sure you come in at half-time a goal to the good.
"The opposition are always going to have a 10-minute spell or so when they're on top.
"We were punished by the one chance they had in the second half."
But Appleton refused to blame the officials for the defeat.
"Decisions are not going for us, but it's not about luck," he said.
"We came again after they had scored, and we had a couple of glorious opportunities to score , but didn't take them."