Reece James looks set to miss England's final World Cup group game against Panama after sitting out training on the eve of the match.
According to Yahoo Sports, the Football Association confirmed James is "following his own programme", as natural back-up Tino Livramento has already withdrawn from the squad with a calf injury.
The 26-year-old played the full 90 minutes in both the 4-2 win over Croatia and the 0-0 draw with Ghana, but is reportedly dealing with a hamstring issue.
Even if James is passed fit, Tuchel may decide against risking him against opponents ranked 42nd in the world, given James has already played two matches in the space of a week.
Given his significant history of muscular layoffs, the coaching staff are highly reluctant to take unnecessary risks with the defender's fitness.
If James is ultimately left out, Ezri Konsa could shift out wide from central defence, while Kobbie Mainoo stands ready to deputise in midfield should Declan Rice not be fit enough to start.
Rice recently revealed he has been dealing with neural pain in his hamstring since the festive period, a condition he has been managing behind the scenes for several months.
On England's wider approach at the tournament, the German added: "There is a long way to go and no one has won a World Cup with four goals per match and going for it. Our responsibility is to bring everything to the table."
With England already assured of a place in the knockout rounds, Tuchel is unwilling to risk aggravating James' injury despite needing a win to guarantee top spot in Group L.
England face Panama on June 28 at New York New Jersey Stadium, with the game their last chance to wrap up top spot in the group.
