Trent Johnston said Ireland had "more or less played the perfect game from ball one" after their 74-run victory over Bangladesh in Barbados.
Porterfield was given the man-of-the-match award for his vital 85
Ireland elected to bat after winning the toss and an opening partnership of 92 by William Porterfield and Jeremy Bray set them on their way to victory.
"I thought they were outstanding - they really set the foundations for our win," said Ireland captain Johnston.
"I can't give those guys enough credit for what they did out there."
Ireland, who beat Pakistan earlier in the tournament, went into the game on the back of a nine-wicket hammering by World Cup favourites Australia and they were determined to come back strongly.
"We spoke about it after the game. We knew we had to get all three disciplines right today and I think we did that," said Johnston.
It wasn't easy but we dug in and managed to come through the early spell and thankfully we got a few runs
Ireland opener William Porterfield
Despite a bouncy track which had some early life Johnston said he never had any doubt it was the right option to bat first.
"The way the Bangladesh spinners were bowling I think the last thing we wanted to do was chase 220, 230 with them on that particular wicket," he said.
"So we made a decision that we were going to go out there and bat first and try to put a competitive score on the board, which we did.
"When we bowled we hoped we could squeeze them with big Boyd Rankin and David Langford-Smith starting up and I thought they bowled fantastically well."
Ireland end their World Cup campaign with a match against Sri Lanka on Wednesday 18 April in Grenada.
"It's a big game. It's the last game for our coach Adrian Birrell and it would be a fitting way to send him off if we put in another display like we did today," said Johnston.
The man-of-the-match award went to Porterfield, who was the only player to pass fifty in the match.
He said: "We weren't too disappointed to bat first - we were looking forward to it.
"We knew there was going to be a bit of pace and bounce but we managed to get past that and set a good total.
"We got stuck to start with. It wasn't easy but we dug in and managed to come through the early spell and thankfully we got a few runs."