Fati, 17, has burst onto the scene at the Camp Nou, scoring four goals in seven La Liga starts and he has now emerged as a top target for Dortmund.
The Bundesliga outfit accept Sancho will move on this summer, with Manchester United at the head of the queue ahead of Chelsea to sign him, and recognise the need to replace his attacking contributions.
Sancho has scored 14 goals and provided 15 assists in Germany’s top flight this season and his loss will be felt by the club.
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But Fati is viewed as having the potential to fill the Sancho-sized hole, according to Sport.
They are not alone in approaching Barcelona over a potential deal and the Catalan giants are willing to allow him to leave on a temporary basis.
Barcelona chiefs recognise the benefits Fati would reap from regular first-team football – something Dortmund could provide.
But they also see his long-term future in Barcelona so they will not allow him to leave on a permanent basis.
They are also weighing up the state of the market before sanctioning any deal.
Should Barcelona fail to land a new attacker in the summer, then Fati will have more opportunities in the first team and could stay.
Fati renewed his contract a matter of months ago and has a release clause of £148million.
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