Bayern Munich's Schweinsteiger has endured an injury-ridden season with an inflamed knee the latest setback to keep him out of action in recent weeks.
Khedira, who formed a solid midfield partnership with Schweinsteiger in the previous two tournaments for Germany, has only recently returned to action after a six-month layoff due to a torn cruciate ligament in his knee last year.
He has played only a handful of games since his recovery, including starting for Real Madrid's victorious Champions League side last week, and only joined his Germany team mates on Monday evening.
Both players appeared to be moving freely on the pitch on a sunny day in the Italian Alps, the site of Germany's pre-tournament training camp.
Keeper Manuel Neuer has been ruled out for at least a few more days and will not train at all in Italy as he recovers from a shoulder injury with team officials insisting his participation was not in doubt.
Germany, who have been drawn with Ghana, the United States and Portugal in Group G, play warm-up games against Cameroon on June 1 and Armenia on June 6 before departing for Brazil.