Manchester City captain Vincent Kompany has had a scan on a calf injury he picked up while training with Belgium.
The 28-year-old central defender missed training on Wednesday and is a doubt for Thursday's friendly with Australia.
"No Vincent Kompany at training," coach Marc Wilmots wrote on Twitter. "He was taken to the hospital for a calf scan. We'll have to wait for the results."
The Premier League champions, who lost 1-0 at home to Stoke last weekend, are away at Arsenal on 13 September.
Any lengthy absence for their skipper would be keenly felt by City, with a key eight-day period in their season about to begin.
After that visit to the Emirates on Saturday week, City begin their Champions League campaign four days later with a formidable trip to 2012-13 champions Bayern Munich, before hosting rivals Chelsea in a crunch Premier League encounter on 21 September.
Of City's central defensive options, £32m summer signing Eliaquim Mangala has yet to feature in a match-day squad since arriving from Porto in mid-August while last season's back-up Matija Nastasic has not made a squad since playing 90 minutes in the Community Shield defeat by Arsenal.