The France international is likely to be available as a free agent this month, despite the Catalan giants remaining hopeful of being able to persuade the winger to sign a new deal.
Dembele was deemed surplus to requirements by Ronald Koeman and his Barcelona career appeared to be over amid a series of disciplinary issues and a poor injury record.
The arrival of Xavi midway through last season coincided with a major revival for Dembele who appeared energised by the signing of his former Borussia Dortmund teammate and great friend Pierre-Emerick Aubameyang.
Xavi is desperate to retain the services of the 25-year-old but Chelsea looks increasingly likely to be his next destination with former Blues defender Johnson describing any deal as a ‘no brainer’.
He told bettingodds.com: ‘I believe it’s a no-brainer. You’ve got to do some clever business. You can’t just go out and spend top dollar for all the best players.
‘If you can get players on the cheap or on a free then it makes absolute sense. You have to think, what would Dembélé cost if he had four years left on his contract?
‘So yes, I think if that sort of deal becomes available then you have to jump at it.’
Chelsea’s new owners are set to back Tuchel with a £200million warchest this summer and will back the German’s judgement if he chooses to press ahead with a move for Dembele.
The Blues failed to keep pace with Manchester City and Liverpool last season and lost out in two cup finals against Jurgen Klopp’s side, losing on penalties on both occasions.
Tuchel is likely to rebuild his forward line during the course of the transfer window with doubts surrounding the futures of Romelu Lukaku, Timo Werner, Hakim Ziyech and Christian Pulisic.
As well as Dembele, Chelsea are also interested in Manchester City star Raheem Sterling and RB Leipzig’s Christopher Nkunku, who scored 35 goals in all competitions last season.
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