England took a major step towards the last 16 of the Women's World Cup with a 1-0 win over Denmark on Friday but their victory was overshadowed by a potentially serious knee injury to midfielder Keira Walsh.

Lauren James scored the only goal of the game in Sydney for the reigning European champions, bending in a superb strike from outside the box in the sixth minute.

Sarina Wiegman's side had more of the possession and more of the chances, but they suffered an almighty fright at the end when Amalie Vangsgaard hit the post with a header.

England's second win in as many games in Group D put them on the verge of the knockout rounds but they still need to avoid defeat in their final pool game against China on Tuesday to be sure.

England are now waiting nervously though to discover the extent of the injury suffered by Barcelona's Walsh, who was stretchered off late in the first half.

Walsh, a key cog in the England team that won the Euro last year, stretched to intercept a pass in her own half and went down in agony.

She immediately signalled to the bench that she could not carry on.

"Of course I'm concerned because she could not walk off the pitch," said Wiegman.

"But we don't know yet (how bad the knee injury is) so we can't make any assumptions. Let's just really wait until we have a diagnosis."

- China stay alive -

China are still alive after a chaotic 1-0 win over debutants Haiti in Adelaide in which the Steel Roses played more than an hour with 10 players.

China looked to be in serious trouble in the last match of the day when they had Zhang Rui sent off in the 29th minute for a clumsy tackle on Sherly Jeudy.

Defeat for China would have ended their World Cup and sent England through, and they were under the cosh for much of the second half.

But Zhang Linyan was brought down in the box by Ruthny Mathurin against the run of play and after a lengthy VAR review, substitute Wang Shuang made no mistake with her 74th minute penalty.

China held on in a wild contest involving several controversial moments.

Haiti were awarded a penalty in second-half stoppage time after Roseline Eloissaint had been seemingly grappled by Chen Qiaozhu, but the referee rescinded it after a VAR check.

China are now level with Denmark on three points and eyeing a spot in the knockout rounds, meaning the group remains in the balance going into the final group matches.

- South Africa denied -

Earlier, Argentina launched a thrilling comeback to deny South Africa a first win ever at the tournament as the sides drew 2-2 in Dunedin, New Zealand.

South Africa were cruising to a historic first win in five matches at the World Cup after goals by Linda Motlhalo and Thembi Kgatlana either side of halftime.

But Argentina pulled one back via a stunning Sophia Braun strike in the 74th minute and then drew level five minutes later when Romina Nunez headed home.

South Africa had lost 2-1 to Sweden in their opening match after also throwing away the lead before conceding the decisive goal in the last minute.

"It is about taking our chances, making better decisions in the final third. If we take our chances we have a different conversation," coach Desiree Ellis said.

"Today was a great opportunity to put ourselves a step ahead, but it is not all lost."

Appearing at their fourth World Cup, Argentina themselves have still never won in 11 attempts.

Argentina and South Africa have one point each in Group G.

Favourites Sweden and Italy have three points before facing off in Wellington on Saturday, ahead of a decisive final round of games on August 2.

Also on Saturday, France face Brazil in a must-win game in Brisbane, while Jamaica play Panama in the same Group F.