England could be without James Anderson for the rest of the third Ashes Test after he picked up a side strain on day two.
The fast bowler pulled up at the end of his his run-up before walking off the pitch to receive medical treatment, leaving England one bowler short.
An ECB statement confirmed the injury but failed to speculate on its severity.
It read: "James Anderson has a tight side and will be assessed overnight and in the morning. There will be an update [on Friday]."
England are in a good position to take a 2-1 series lead as they restricted the tourists to 168-7 in their second innings.
They trail by 23 runs with just three more wickets to take, while Peter Nevill remains not out for Australia.