England forward Raheem Sterling is flying out to join the Chelsea squad in Los Angeles prior to his transfer from Manchester City.
It is expected the move will be officially announced in 24 to 48 hours.
Chelsea are training at UCLA and Sterling could be available to play in their opening tour match in Las Vegas on Saturday against Club America.
Tuchel’s men then face Charlotte FC in Charlotte on Wednesday, 20 July before taking on Arsenal in Orlando on 23 July.
Sterling has one year left on his contract at Premier League champions City, who signed him from Liverpool in a £49m deal in 2015.
He has scored 131 goals in 339 games for Pep Guardiola’s side.
When the deal is completed, it will make Sterling – who has 77 England caps – Chelsea’s first major signing since they were taken over by a consortium led by Todd Boehly this summer.