Russo has been at United for the last three years and has scored 27 goals in 59 games, but last season's WSL runners-up have been unable to convince the 24-year-old to stay.

Sky Sports News understands United and Russo have been discussing terms over a new deal for the last 18 months but United only reached the forward's contract expectations on the last week of the season, at which point it was too late to entice her to stay.

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United's delay came despite Marc Skinner's side receiving two world-record bids from WSL rivals Arsenal for Russo in January.

The forward is one of the top free agents in football this summer and her signing would send a telling message of intent to the rest of the game.

Sources claim a number of clubs around the world, including in the USA, France, Spain and the UK, want to sign Russo this summer, but Arsenal have positioned themselves as frontrunners following their interest earlier this year.

However, Russo's sole focus at the moment is England's World Cup campaign in Australia and New Zealand, which begins next month.

Man Utd's offer too late to tempt Russo

Sky Sports News reporter Anton Toloui:

Alessia Russo was always going to be a player the top sides in world football wanted. Arsenal signing her would be a huge coup.

They look like they have fought off competition from the biggest clubs in the US and Europe as they look to fire their way back to the top of the WSL.

Manchester United have wished Russo well in her future endeavours and there's no hard feelings between either party. But negotiations, which went on for a year-and-a-half, bore frustrations on both sides.

United did offer Russo a "considerable" deal to become the club's highest-paid player but it was felt the final offer came too late.

Russo's exit, plus Ona Batlle's expected departure for Barcelona, leaves United with two huge holes to fill as they look to build on last season's second place in the league. The club will have to spend big if they're to replace two of the league's top stars.

As for Arsenal, Russo's expected arrival bolsters a staggering strike force, especially when Vivianne Miedema and Beth Mead are fit enough to return.

Stoney: Russo not moving to NWSL

Casey Stoney, the manager of San Diego Wave and Russo's former boss at United, said she would have been keen to take the striker to the NWSL.

Speaking on Thursday, Stoney told reporters: "Trust me, if Alessia Russo was coming to the NWSL, I would be in the conversation.

"She was my mascot when she was a kid. I signed her at United. I have a very good relationship with Alessia.

"When it comes to players like that, you're already having conversations. You're already making sure that you're on the table when it comes to them making a decision.

"She's not coming here."

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