With Colombia and South Korea facing off today, every nation in the World Cup will have played a game by the final whistle in that match.

So we've seen minnows take it up to giants, favourites assert their dominance, and a slip of the tongue about Sam Kerr that had media managers scrambling.

Here's the five talking points heading into day five of action.

1. Colombian teenager on incredible journey back from cancer

At 15, Linda Caicedo, now a star forward on Colombia's Women's World Cup roster, received a crushing diagnosis. She had ovarian cancer.

Caicedo already had made her debut for Colombian professional team América de Cali and the Colombian senior women's national team.

With this news, though, her soccer career seemed over.

"I remember I was going into surgery one day and I was feeling really bad," Caicedo said.

"Because I thought that I was not going to be able to play top-level football again."

The Colombian women's team head coach, Nelson Abadía, provided words of encouragement over the phone.

"He said, 'no, just relax'," Caicedo recalled.

"'You're going to come back'."

She's now one of the best young players in the world.

The 18-year-old Caicedo is expected to make her Women's World Cup debut in Colombia's opener against South Korea at midday today (AEST) at the Sydney Football Stadium.

To those battling cancer, Caicedo has a message: "I am an example that you can get out of that and overcome this."

The match also could mark the World Cup debut of 16-year-old South Korea forward Casey Phair. Born to a Korean mother and American father and raised in the US, Phair is not expected to start. Should she play, she would become the youngest player ever to play in a World Cup, men's or women's.

2. BBC apologises for question to Moroccan captain on gay players

The BBC was forced to apologise for an "inappropriate" question from one of its reporters, directed at the captain of the Morocco women's national team.

At a press conference ahead of Morocco's opener against Germany, a reporter asked Ghizlane Chebbak a question that left the panel visibly confused and uncomfortable.

"In Morocco, it's illegal to have a gay relationship. Do you have any gay players in your squad and what's life like for them in Morocco?" the reporter said.

The press conference moderator interjected, saying: "Sorry, this is a very political question, so we'll just stick to questions relating to football."

"No, it's not political," the journalist replied.

"It's about people, it's got nothing to do with politics. Please let her answer the question."

A BBC spokesperson later acknowledged the question was inappropriate. 

"We recognise that the question was inappropriate," they said.

"We had no intention to cause any harm or distress."

Shireen Ahmed, a reporter for CBC Sports, wrote that the reporter was "completely out of line."

"Harm reduction matters and posing the question to the captain or coach was unnecessary," she said.

"Asking a player about her teammates and whether they are gay and how it affects them when you know it is not permissible is bizarre and out of line. The captain cannot out players nor comment on policy [because] it could be dangerous for them, too.

"If reporting harms someone, it is not only unethical but dangerous."

3. Ticket sales hit 1.5 million as record looms

A New Zealand family of five purchased the tickets that took the sales total to 1.5 million for the Women's World Cup on Monday.

Soccer's world governing body says the tournament, being co-hosted by Australia and New Zealand, is on track to be the best-attended in the competition's history.

FIFA said the 1,500,000th ticket went to Auckland woman Maria Strong, who bought tickets for her husband and three children to attend Italy's Group G win over Argentina at Eden Park as part of a family celebration for her son's 12th birthday.