Australia batsman Chris Rogers retired hurt on 49 on the fourth morning of the second Ashes Test after experiencing a dizzy spell.
Rogers, 37, signalled to the dressing room after the second over of the day at Lord’s before slumping to his knees.
He was given medical attention then helped off the field.
Rogers was hit on the helmet by a James Anderson bouncer on the second day. However, there is no indication the events are related.
He missed Australia’s two Tests in West Indies in June through concussion after taking a blow to the head in training, and complained of headaches and dizzy spells for some time afterwards.
Rogers made a Test-best 173 in the
as Australia posted 566-8 declared before bowling out England for 312.
Australia were 114-0 in their second innings when Rogers, who was 44 not out overnight, left the field.
They eventually declared on 254-2, setting England a Test record 508 to win or, more likely, bat out five sessions to secure a draw.
Cricket Australia said Rogers rested in the dressing room and did not require hospital treatment, although he did not field when England began their innings.