Khedira has missed most of the season so far with thigh injury and has made just one Serie A appearance since the middle of September.
The German international could now miss Juve's home game against SPAL on November 24, and may also be absent for the Champions League visit of Valencia three days later.
A statement released on the club's website said: "During the workout, Sami Khedira reported a sprained left ankle, with the player immediately beginning his recovery and will be monitored daily, the German is now a big doubt to face SPAL."
It was the last work out for the club until Tuesday, when the first of Juventus' players away on international duty return.
The latest setback to the former Real Madrid man means Juventus face something of a midfield injury crisis with Emre Can and Miralem Pjanic both doubtful for the Old Lady’s next game.
It could mean that Juve are left with just two fit centre-midfielders for the time being, in Blaise Matuidi and Rodrigo Bentancur.
Juve are currently six points clear at the top of the Serie A table, as the reigning champions seek to win an eighth straight league title.
The Old Lady have only dropped points once in the domestically this season, when they drew 1-1 against Genoa in October.
They also are on course to qualify from their Champions League group, despite the recent defeat to Manchester United. A win against Valencia in two weeks would confirm Juve’s place in the round of 16.