The Germany international will compete with Claudio Brava and Jordi Masip for Barca's first-choice spot in goal this season with coach Luis Enrique yet to be decided on who will be his starting shot-stopper.
But Ter Stegen, who moved to Camp Nou from Borussia Monchengladbach earlier in pre-season, may be set for a potentially crucial spell on the sidelines after picking up an injury on Monday.
A Barca statement revealed he will undergo tests on Tuesday to determine the severity of the issue, and did not put any timeframe on his potential recovery.
It read: "New first-team goalkeeper Marc-Andre ter Stegen suffered a lumbar contusion during the second of Monday’s two training sessions.
"The club doctors will examine the extent of the back injury on Tuesday, which should shed more light on his availability for training."
Barca's pre-season preparations are now in full swing with the club's World Cup stars, including Lionel Messi, Xavi and Neymar, returning to action as they look to improve on last season's disappointing campaign under Gerardo Martino.
One player unavailable to Luis Enrique is recent acquisition Thomas Vermaelen - the defender is yet to recover from a hamstring injury sustained in Brazil with Belgium.
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