The two Lionesses shot to fame as they starred in England's Euro 2022 triumph on home soil, becoming trailblazers for aspiring footballers across the country.
But aside from playing alongside each other at international level, the England pair have also grown up together, becoming friends at age 12 and then later playing and even living together whilst at Manchester United.
As a result, the duo have not only built a fantastic relationship on the pitch - as shown by Russo setting up Toone for her history making semi-final goal - but have also become, as they've put it, 'best friends' off of it.
Their strong bond has even contributed to a fan-inspired chant that goes 'Tooney and Lessi Russo' to the tune of Rockin' All Over the World by Status Quo.
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Lionesses fans have loved watching content of the pair doing hilarious challenges and pranks online, with Russo having a lobster thrown at her in one video that had her terrified and her teammates in hysterics.
But it's United fans that will feel particularly sore following Russo's high profile departure following the end of her contract.
The 24-year-old has since signed for Arsenal on a free transfer - following Man United's record breaking £500,000 bid in January - with her rejecting multiple new contract offers from the Red Devils.
After three years as teammates at club level, it's no surprise the pair are just as gutted as their fans that they won't be glued at the hip anymore.
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Taking to TikTok after the announcement of Russo's departure, Toone bid an emotional farewell to her pal, telling her 421.9k followers: "Away from football, I just wanted to say best of luck to my best friend Alessia, moving clubs.
"I'm really proud of you and hope you smash it, I'm definitely going to miss you and spending time with you every single day.
"But I know you'll be great and I know we'll be friends forever. Love ya, miss ya and enjoy it."
It's clear Russo has the same affection for her Red Devils pal, too.
Speaking to GQ about their friendship just before her move, Russo said: "There are so many highs and lows in football and to have a constant in your best friend throughout that is really nice.
"We've seen each other at our best and worst. We've had the highest of highs last summer winning the Euros together, and had some tough points too, but that just makes the friendship stronger. We've been friends since we were 12 or 13, and we'll be friends forever."
Toone then hilariously responded with the iconic jibe from 'The Inbetweeners: "Ooh, friends!"
Changing back to a more serious tone, the midfielder then continued: "Like Less said, it's nice to have someone there who's been through it all and understands it. Not many best friends can say that they've won the Euros together.
"In football, people move on, but you have friends in football that you have for life. They're very special because they understand the journey and they know what it takes to get to the top.
"To have Less by my side since we were young girls has been really nice and hopefully we can keep making lots more memories - and keep winning trophies."
Their teammates can see their inseparable bond too, with former England star and Euro 2022 winner Jill Scott exclusively telling talkSPORT just how strong their connection is.
"They're great friends off the pitch and obviously they connect very well on it as well. They've had that relationship at Manchester United for the last few seasons and you can really see that strong
connection," she said.
"That's why they play so well together. You've also got Keira Walsh and Georgia Stanway who have a similar friendship, but once
everybody steps over that white line I can really say that the Lionesses have a great togetherness."
Although they won't be able to win those trophies together domestically, Toone and Russo will of course be aiming to do so on the international stage.
That can become a reality this Sunday when England face Spain - a side they knocked out at Euro 2022 - in the Women's World Cup final this weekend.
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We can't wait to see their TikTok content should they lift the trophy together.