The women’s World Cup kicks off in 100 days

The Women's World Cup countdown has begun in earnest.

Wednesday marks 100 days until kickoff for the game's biggest tournament, opening on June 7 in Paris. The 24-team event will be played at nine stadiums in France over the course of a month, with the final set for July 7 in Lyon.

The United States is the defending champion, having won the 2015 World Cup in Canada. The top-ranked Americans are also the presumptive favorites this time around.

So far, ticket sales have been strong. French newspaper L’Équipe reported on Wednesday that more than 500,000 tickets out of 1.3 million available have been sold so far, following the ticket package launch and the presale phase.

Half of the sales have been to buyers outside France. The U.S.' tournament opener against Thailand, set for June 11 in Reims, is already almost sold out.

Earlier this month, FIFA said that 25 percent of all tickets sold overall up to then had been bought by fans in the United States.

Single-match tickets go on sale March 7.

There are a few lingering controversies hanging over the event, including prize money. Last October, the FIFA Council raised the prize money from $15 million in 2015 to $30 million in France. But by contrast, the prize pool for the men’s World Cup in Russia last year was $400 million.

In 2015, the U.S. women received $2 million for raising the trophy, and the winner this summer will earn $4 million. The French men, who won their World Cup, earned $38 million.

While the men's World Cup generates far more revenue, critics say FIFA should back up its pledges to grow the women's game with investment and incentives — like a sweeter prize pool.

"We need to try to find what is the most balanced way, and I think we made a step and there will be many more steps going ahead," FIFA President Gianni Infantino vowed when the increase was announced.

Another issue is timing. FIFA has been criticized for scheduling the Women's World Cup final on the same day as the men's Copa America final and the CONCACAF Gold Cup final.

Here are some other things to watch in the 100 days leading up to the World Cup.

The next Women’s World Cup milestone for FIFA is confirming the use of video review.

The prospect of VAR in France looked in doubt as FIFA prevaricated when asked if women’s players would benefit from the same technology as debuted at the men’s World Cup in Russia last year.

But FIFA confirmed its Women’s World Cup referees were training with VAR earlier this month. The FIFA Council has to ratify the use of VAR at a meeting in Miami next month.

Australia shocked many with January’s dismissal of coach Alen Stajcic, who had been coach of the Matildas since 2014 and still had nine months left on his contract.

The Australian federation said it fired Stajcic following an internal review and Ante Milicic was named to take over through the World Cup.

Milicic is not the only one jumping aboard a team so late in the process. Cameroon coach Joseph Ndoko was replaced by Alain Djeumfa in January. Known as the Lionesses, Cameroon advanced to the knockout round in Canada but the team has struggled recently with preparation for France.

The move was somewhat of a surprise because Ndoko had guided the team to a third-place finish at the Women' Africa Cup of Nations late last year, qualifying Cameroon for the World Cup.

The 100-day mark also means teams are going all-in on preparation for the event. The United States is hosting the SheBelieves Cup with Japan, England and Brazil — all World Cup-bound teams — starting on Wednesday. There’s also the annual Algarve Cup in Portugal, which starts Thursday and features Canada, Sweden, Spain and several other teams.

Australia is hosting the inaugural Cup of Nations, which will also include New Zealand, Argentina and South Korea, starting Thursday.

"We've got eight games left," U.S. coach Jill Ellis said Tuesday about the remaining schedule. "Every minute we can get the players together to forge those relationships is really important."

But there's far more urgency for teams that normally don't have many regular exhibition games. Chile and Jamaica, who will each make their World Cup debut in France, will play a pair of matches in Jamaica, with the first on Thursday in Kingston.

"Chile have played Brazil and Italy recently, therefore we'll get an opportunity to measure where we are as a team," Jamaica coach Hue Menzies told reporters last week. The Reggae Girls, ranked No. 53 in the world, are also expected to play a friendly against Panama as the team prepares for the World Cup.

Sponsors are also gearing up for the tournament. Adidas unveiled the official World Cup game ball on Wednesday.

U.S. goalkeeper Alyssa Naeher was on the champion 2015 squad, albeit as a backup to goalkeeper Hope Solo. Now the presumed starter in France, Naeher is tempering her excitement with focus on the work to be done — starting with the match against Japan on Wednesday.

"My mindset has kind of always been taking everything one game at a time. My focus is going to be on Japan and how we can put together a good performance and come away with a win. Then we move on to the challenge that England brings us in a few days," Naeher said Tuesday. "I mean, yes it's exciting to start a countdown like that (the 100 days) and it kind of builds the excitement around the whole event. But for me it's kind of staying focused in the moment."

Norway coach Martin Sjogren told the BBC that there is no chance Ballon d’Or winner Ada Hegerberg will play in the World Cup. Hegerberg stepped away from the national team out of what she said was a lack of respect for the female players. Sjogren said discussions were held, but ultimately Hegerberg decided not to play.

Staff writer Jonathan Tannenwald and AP global soccer writer Rob Harris in London contributed to this report.