Rampant title contenders Spain and former champions Japan became the first teams to reach the Women's World Cup last 16 on Wednesday as both won with ease.

 Two-time Ballon d'Or winner Alexia Putellas started for Spain following her serious knee injury and played her part in a 5-0 demolition of Zambia.

Japan had been on the brink of reaching the knockout rounds following their 2-0 win over Costa Rica earlier in the day and the Spain result sent both of them sailing through.

In the final match of the day, Olympic champions Canada took a step towards the next round by fighting back from a goal down in soaking-wet Perth to win 2-1 against Ireland, whose hopes of progressing are over.

Japan and Spain meet on Monday to decide who wins Group C, and with it a theoretically easier draw. Both have a perfect six points from two games and are yet to concede a goal.

Costa Rica and Zambia play the same day in the fight to avoid finishing bottom of the pile.

Barcelona's Putellas came off at halftime at Eden Park in Auckland but Zambia were already dead and buried by then with Spain two goals in front against the lowest-ranked team in the tournament.

Jennifer Hermoso and Alba Redondo both scored twice in the victory in front of just over 20 000 spectators, but Spain coach Jorge Vilda warned their best was still to come.

"We haven't seen the best version of Spain, that is absolutely clear," said Vilda.

"After the second goal we took our foot off the pedal and that is something we need to correct. We can't settle for this," he added.

JAPAN THROUGH, CANADA SURVIVE

The 2011 champions Japan beat an error-prone Costa Rica comfortably in front of 6 992 spectators in Dunedin, the smallest crowd at the finals yet.

Japan, who began their campaign by thrashing Zambia 5-0, were never in trouble against an outclassed Costa Rica at the nearly 30 000-capacity Dunedin Stadium.

The game was effectively killed off in the space of three first-half minutes with goals from Hikaru Naomoto and 19-year-old Aoba Fujino.

In Group B, World Cup debutants Ireland took the lead against Canada after just four minutes when captain Katie McCabe scored direct from a corner.

But an own goal in the tricky conditions brought Canada level just before halftime and then Adriana Leon scored what turned out to be the winner in the 53rd minute to end Ireland's World Cup hopes.

Canada top the group with four points from two games, but Australia will look to leapfrog them by beating Nigeria on Thursday.

The co-hosts Australia must do with only one recognised striker after Manchester City's Mary Fowler was ruled out of the match with concussion.

The Matildas were already missing captain and talismanic striker Sam Kerr, who was ruled out of at least the first two matches of the tournament with a calf injury.

Arsenal's Caitlin Foord is now Australia's only recognised fit striker.

US-NETHERLANDS CLASH

Thursday's action is headlined by a heavyweight clash between the United States and the Netherlands in Wellington.

Both teams will expect to get out of Group E, so bragging rights and group supremacy are at stake in a re-run of the 2019 final.

On that occasion the Americans won 2-0 and are pursuing an unprecedented third successive World Cup title.

The Netherlands are not quite the force they were but coach Andries Jonker believes the rest of the world, the Dutch included, are closing in on the United States.

"Are we getting closer? The feeling is yes," he said

"Tomorrow is the first time we can check if we are closer or not."