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Tonight is one of the biggest games in the history of the England women's team, as the Lionesses take on the number one ranked women's team in the world - USA.

On both sides there are strong players, and both sides are undefeated in this World Cup so far.

But how do the different teams match up?

Newsround has spent hours and hours in the lab, analysing who could be the key match-ups when the two teams face each other tonight in Lyon.

Find out who the star players are and how they could decide the fate of the World Cup Final!

Lionesses captain Steph Houghton will face a big test as she comes up against joint-top scorer in the competition, USA captain Alex Morgan.

The American superstar striker has 5 goals and 3 assists so far, but all of those goals came in a 13-0 win against Thailand at the start of the competition.

Although the USA are the tournament's top scorers - currently 11 goals ahead of any other team, England have the best defensive record.

Phil Neville's Lionesses have only let in one goal this World Cup.

Megan Rapinoe has made the headlines this summer - she's had a brilliant World Cup, and is matching Alex Morgan's 5 goals and 3 assists so far.

The left-winger has scored four goals in her last two games against France and Spain, and her confident goal celebration caught the world's attention.

If there's anyone who can stop her though, it's England's superstar right-back Lucy Bronze.

Manager Phil Neville recently called her "the best player in the world, without a shadow of a doubt" and it's clear to see why.

Bronze is a two-time PFA Women's Player of the Year, a two-time Champions League winner - and she's got a hammer of a right foot!

Ellen White has been England's star striker this World Cup. She also has 5 goals, level with Rapinoe and Morgan.

But White might have to step it up a level if she wants to beat the USA 'Keeper Alyssa Naeher.

She hasn't let in any goals in the group stages, and showed her great reflexes against France to keep USA in the lead.

Both players will need to be on top form if they are to get their teams to the finals.

This midfield battle could determine how the whole game is played.

Lioness Jill Scott is now England's most capped World Cup player in English football - that's for both women's or men's.

Although she only has one goal this competition, her work rate has made her a vital part of the squad.

But the same could be said for USA's Samantha Mewis.

Playing in her first World Cup, her two goals and three assists so far in the competition has pushed her into Jill Ellis' starting 11.

Mewis is the tallest player in the USA squad, so is a threat from set pieces, but also has bags of pace and energy that can impact a game. She is definitely one to watch.