England captain Joe Root is in hospital in Sydney suffering from severe dehydration.
Root had diarrhoea and was vomiting before being admitted to hospital.
It is unclear whether he will be able to resume his innings this morning.
Sydney was the hottest place on Earth yesterday, with with temperatures at the SCG reaching 47 degrees.
A heat stress tracker registered 57.6 degrees at the ground during the day.
Root was in the field for all bar 35 balls of the day, first in the field with England, then coming in at 2/15 after 5.5 overs.
He had battled to stumps unbeaten on 42 off 124 balls as England tried to avoid an innings defeat to make the series 4-0 to Australia.