The four-time winners USA reached the knockout stages after holding off the debutants, as they spurned several chances to score at Auckland's Eden Park.

With the minutes ticking away in the affair, striker Ana Capeta took a shot and 42,958 fans held their breath as they watched the ball ricochet off the post and leave a tearful Portugal team to wonder what could have been.

Had it gone in, it would have handed the Americans their first group-stage exit and marked an extraordinary upset in a tournament that has been filled with surprising results. Instead, Portugal were packing their bags.

"When Ana shoot I was thinking it will be (a) goal and what Vlatko will do and what I have to do to stop (him)," Portugal coach Neto told reporters.

"I truly believed that the goal will be in that moment and I was starting to think 'What can I do to help my players if you are winning 1-0?'"

Portugal leave New Zealand with their heads held high after a credible first appearance at the tournament. They lost 1-0 to 2019 finalists the Netherlands in their opener before beating Vietnam 2-0.

"What I said to the girls - I was very proud," said Neto.

"Of course, they are very sad because we have huge expectations of ourselves... they felt it was probably the first team in the world that will eliminate the USA in this stage, round. It was a huge opportunity for us."