Holders Japan have the luxury of tinkering with their tactics as title rivals the United States play for a spot in the last 16 in the final group game at the Women's World Cup on Tuesday.

Japan eased into the next round of the 24-team tournament with a game to spare after wins over Switzerland and Cameroon in Group C with minnows Ecuador next on their radar in Winnipeg.

The United States lead Group D with four points after following their opening 3-1 win over Australia with their first ever goalless draw in the tournament against Sweden in front of a sellout crowd of 32,716 at Winnipeg Stadium.

The USA now play for top spot in the group in Vancouver in their final group game against African champions Nigeria.

"We're still in the driver's seat. We still have an opportunity to finish top if we get things done against Nigeria," said USA coach Jill Ellis, whose side would meet 2007 runners-up Brazil by finishing second.

"We're not taking anything for granted, It's not labelled the 'Group of Death' for nothing," she added.

Japan coach Norio Sasaki already has his eyes focused on the knockout rounds.

"Psychologically it helps that we will be advancing to he next stage," said Sasaki.

"We're preparing for the next round as we approach the next match (against Ecuador).

"Our initial objective was to proceed to the knockout round, we've achieved this. We're now preparing to proceed and advance further."

Sasaki said that despite a few injury concerns it was uncertain whether veteran star Homare Sawa, competing in a record sixth World Cup, would line out after starting on the bench against Cameroon.

"It will depend on the training today (Sunday) but she is well, very energetic," he said.

Ecuador are ranked 44 places below the fourth-ranked Asian champions and coach Vanessa Arauz said they wanted to finish on a positive note.

"It's difficult to have 16 goals scored against you, but I feel success and defeat are two sides of the same coin," said Arauz, at 26 years the youngest coach in a FIFA tournament.

"We want to hold our heads up high despite having little time to recover from the defeats and show that we have good potential for the future."

Switzerland and Cameroon, both on three points, go head-to-head for the second automatic qualifying spot from Group C in Edmonton, which would assure them of playing the next match there.

Behind Olympic champions the United States, winners in 1991 and 1999, are Australia, second on three points after defeating Nigeria 2-0, with Sweden on two and Nigeria on one.

"I think it will be a great game, a very spirited team, some great players, this is a most athletic group, it will be a really good match for us," said Ellis.

The Americans would advance to the knockout stage if they finish first or second, but can also advance by finishing as one of the top four third-place finishers across the six World Cup groups.

Alen Stajcic's Australia can also finish top as the Matildas seek revenge against the Swedes who knocked them out in the last 16 four years ago.

"There's still a lot to be played in this group," said coach Stajcic.

"Everything is up for grabs still, so we're not taking anything for granted.

"We can finish top of the group if USA drop points, we can still finish second if we beat Sweden or possibly even draw that game.

"That Nigerian team, anything can happen when you play them. They're so spirited, good positive footballers and you just don't know what to expect, they can produce anything.

"They've (Sweden) probably got four or five of the best players in attack in this World Cup. A bit like Nigeria, a very potent attacking line. We're going to have our hands full again."

Fixtures (all times GMT)

Tuesday, June 16

Group C

Ecuador v Japan at Winnipeg (21:00)

Switzerland v Cameroon at Edmonton (21:00)

Group D

Nigeria v USA at Vancouver (00:00 GMT - Wednesday, June 17)

Australia v Sweden at Edmonton (00:00 GMT - Wednesday, June 17)