VANCOUVER - Holders Japan and Olympic champions the United States both kept their title challenges on track as they advanced to the last 16 at the Women's World Cup on Tuesday as group leaders.
The United States, beaten in the 2011 final by Japan, eliminated Nigeria 1-0 in front of their passionate fans in Vancouver's BC Stadium to lead Group D, after the Japanese had earlier beaten Ecuador 1-0 to top Group C.
Surprise African newcomers Cameroon are the only side from the continent left as they beat Switzerland 2-1 to advance second in Group C as Australia finished second in Group D after holding Sweden 1-1 in Edmonton.
"I think the crowd was amazing and that had a big part in our game tonight," said USA coach Jill Ellis of the capacity crowd of nearly 53,000 at BC Place Stadium.
"I'm pleased with how we played and pleased to be moving out of a tough, tough group," she added of a Group D dubbed the 'Group of Death'.
Captain Abby Wambach scored her 183rd international just before half time off a Megan Rapinoe corner to set the side on their way.
The 35-year-old now has 14 World Cup goals just one shy of Brazil star Marta's record 15, achieved earlier in the tournament.
Nigeria's defence had been hit by Ugo Njoku's suspension and the African champions were down to ten women for the final 20 minutes after defender Sarah Nnodim was sent off for second yellow card.
The result means the USA advance to the knockout round as Group D leaders with seven points, with Australia on four and Sweden three.
Nigeria are eliminated with just one point.
"I don't think they (USA) were very good it was a lack of concentration on our part," said Nigeria coach Edwin Okon who refused to shake Ellis's hand after the game.
"They were just lucky to win today. She (Wambach) only got that goal because of a lack of concentration from our defence." As first in Group D the USA next meet one of the four best third-placed finishers from another group in Edmonton next Monday.
A draw was good enough to see Australia through for their third consecutive tournament, and they next play Brazil in Moncton on Sunday.
Captain Lisa De Vanna scored after five minutes for the Matildas but ten minutes later 2003 runners-up Sweden levelled thanks to Sofia Jakobsson at Edmonton's Commonwealth Stadium.
Cameroon fly African colours
Japan's Yuki Ogimi scored after just five minutes in Winnipeg for Japan against 48th-ranked Ecuador.
Japan top Group C with nine points, with Cameroon on six. Switzerland have three points with Ecuador on the way home with none.
Coach Norio Sasaki's side will also next face one of the four third-place finishers to advance in Vancouver next Tuesday.
"It was good to score early tonight, we should have scored more but we weren't able to. They were very persistent in their defence," said Sasaki.
In Edmonton, Cameroon came from behind to beat Switzerland, who had taken the lead when Ana Maria Crnogorcevic scored after 24 minutes.
But Cameroon were transformed after the break.
Goals from Gabrielle Onguene after 47 minutes and a powerful header from substitute Madeleine Ngono Mani on 62 sealed all three points for the 53rd-ranked side.
It is only the second time that an African side have made it out of the group stage after Nigeria in 1999.
"Compared to Nigeria, Cameroon are a small team, we're not just representing Cameroon but carrying the colours of Africa," said coach Enow Ngachu.
As second-placed finishers in Group C Cameroon next play Group A runners-up China in Edmonton on Saturday.
Sweden and Switzerland must now wait to see if they finish as one of the four best third-placed finishers across the six groups.
The tournament continues on Wednesday with the final round of group games.
In Group E Brazil play Costa Rica and Spain are up against South Korea, while in Group F France take on Mexico and England up against Colombia looking to seal a place in the knockout rounds.