Real Madrid superstar Cristiano Ronaldo opened the scoring from the penalty spot after 33 minutes at Saint Petersburg Stadium, while Bernardo Silva scored the second goal for the Iberian squad just five minutes later.
The New Zealand side maintained 2-0 trashing status quo till 80th minute when Andre Silva scored the third goal and Luis Carlos, popularly known as' Nani' crowned the goals in the first minute of extra time. Santos said afterwards that New Zealand's performance against Mexico, when they narrowly lost 2-1, put him on alert about the problems they could pose - which probably explains why Ronaldo, who was withdrawn midway through the second half, and Portugal's other big guns were picked from the start.
Portugal head into the semifinal as winners of Group A, ahead of Mexico on group difference after the CONCACAF champions beat hosts Russian Federation in Kazan 2-1 in an incident-packed game.
According to organizers, a total of over 41,500 people attended tonight's match at Kazan Arena.
Portugal's Nani, 2nd left, scores his side's fourth goal during the Confederations Cup, Group A soccer match between New Zealand and Portugal, at the St. Petersburg Stadium, Russia, Saturday, June 24, 2017.
It was 2-0 four minutes later when Bernardo Silva slipped a shot into an unguarded goal after neat play on the left flank between Ricardo Queresma and Eliseu. Russia's hopes of a comeback were further hampered in the final 20 minutes when Yury Zhirkov was sent off for a second yellow card.
Russia national team manager Stanislav Cherchesov has taken full responsibility for Russia crashing out of their home FIFA 2017 Confederations Cup at the group stage.
Russian Federation was the lowest-ranked team in the eight-nation competition among continental champions plus the World Cup victor and the host nation.
After conceding the first goal in the 25th minute, Mexico came from behind to beat the hosts.
What was perhaps unusual was Saudi Arabian referee Fahad Al Mirdasi pulled the game back a couple of minutes after the incident for it to be reviewed by the Video Assistant Referee (VAR). Porto midfielder Herrera fired in a deep cross to the far post where Araujo lifted the ball over Akinfeev and into the opposite corner. Play had continued for about 30 seconds before the game was stopped for the review.
Mexico finished second in Group A with seven points, behind Portugal on goal difference.
Akinfeev failed to clear a bouncing ball, allowing Lozano to sneak in and score the victor seven minutes into the second half.