Sam Kerr, widely regarded as one of the best strikers in the world, has joined Women's Super League leaders Chelsea.
She is the all-time leading scorer in the National Women's Soccer League in the US and the Australian W-League.
Kerr, 26, has signed a two-and-a-half-year deal and is available for the second half of the season from January.
"The fact she chose Chelsea when she could have gone to any club in the world is a testament to the players and the staff here," said boss Emma Hayes.
Former Chicago Red Stars and Perth Glory player Kerr scored five goals at the World Cup this summer, leading Australia to the last 16.
Kerr said: "The WSL is the best league in Europe. I want team success and I don't want it to come easy.
"I feel Chelsea have been building something special over the years and I want to be a part of that - I want to lift some trophies."
Chelsea fought off interest from a number of top European clubs including six-time Champions League winners Lyon, Bayern Munich and Real Madrid.
Kerr could have earned more money elsewhere but the opportunity to work with Hayes and live in London, where she has family connections, are among the reasons she opted for Chelsea.
She also wanted to end the cycle of playing in the NWSL and W-League back-to-back, as she has done in the past few seasons.
"Sam has proved time and time again in the NWSL that she is a prolific goalscorer," Hayes added. "She's won the golden boot many times and she's a player that can make things happen, but she's also a fantastic team player.
"She saw this as the best place for her to grow and take the next step in her career. That's a wonderful compliment to us all."
Kerr is the ninth player from Australia to play in England, following the likes of Emily Gielnik (Liverpool), Tanya Oxtoby (Doncaster Belles) and Caitlin Friend (Notts County).
On Monday, Australia's Optus Sport signed a three-year deal with exclusive live rights for the WSL, and will broadcast about 50 matches a season in Kerr's home country.
Why was Kerr in demand?
There are not many players who can outscore Kerr.
She dominated the Australian W-League, which she featured in from October-April with Perth Glory, and the National Women's Soccer League in the US, where she played for Chicago Red Stars from April-September.
Her 70 goals in the W-League are an all-time record and she has finished as top scorer for two successive seasons.
Kerr also tops the all-time charts in the NWSL with 69 goals and picked up the Golden Boot for three years in a row - her latest tally of 18 being the highest in a single campaign.
|Sam Kerr's stats in the NWSL|
She scored 44% of Chicago Red Stars' total number of goals this season and finished fifth in the league with five assists - after getting 17 goals in 13 appearances for Perth Glory last season.
On the international stage she is just as good.
With 38 goals in 83 appearances, Kerr sits joint-third in the all-time standings for Australia. The only player still active with more goals is Australia co-captain Lisa de Vanna (47) who plays for Italian side Fiorentina.
Why has she chosen Chelsea?
While Kerr has proven herself in the NWSL and the W-League, she is yet to test herself among Europe's elite and that might have been a factor in her exclusion from recent player awards.
Many of the best players in the world, including Ballon d'Or winner Ada Hegerberg and Uefa Player of the Year Lucy Bronze, are competing in the Champions League with their clubs.
Chelsea reached the semi-finals of the competition last year, but finished third in the WSL, meaning they missed out on qualification this year.
They are top of the league, a point above champions Arsenal after five games.
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