Chris Rogers had to retire unwell on the fourth morning of the second Ashes Test at Lord's after experiencing a "sudden dizzy spell".
Rogers was hit on the helmet by the first ball of the second day, a delivery from James Anderson, having made 158 at that point of his first-innings 173.
The opener also had to miss both matches in Australia's recent series in the West Indies after suffering concussion in net practice.
But there was no suggestion from the Australia camp of any connection between those incidents and the reason for Rogers retiring not out on 49 this time.
He appeared to suffer some disorientation in the middle after the second over of the morning as he and David Warner were extending Australia's huge lead, having resumed on 108 for none in their second innings.
After sitting down for a few moments, he decided to go off - one run short of what would have been a ninth half-century in his last 10 Test innings.
A team spokesman later said: "He felt fine (before batting) this morning, but then felt a sudden dizzy spell."
Rogers did not go to hospital but, after consulting Australia's team physio, instead rested at the ground.