Tuchel’s squad is brimming with midfield and offensive options and Ross Barkley and Hakim Ziyech are both dispensable rather than the future.
Barkley has made just one Premier League start all season and at 28 needs a transfer to kickstart a career revival.
Ziyech, meanwhile, has flattered to deceive since joining from Ajax and has been linked with moves to Inter Milan and Barcelona, among others.
Both players cost big money for Chelsea but are now surplus and can free up the squad space needed for Gallagher, as well as funding other transfers.
Gallagher looks destined for Stamford Bridge stardom and Tuchel can signal his intent to utilise another Cobham asset with two sales this summer.