Australia captain Steve Smith won the toss and chose to bat in the second test against South Africa on Friday.
Australia, coming off a 118-run win batting first in the opening match in Durban, will aim to set another good total at St. George's Park, where there was some light drizzle on the first morning.
The toss was delayed for 10 minutes because of that rain but the weather was expected to clear up quickly.
Australia retained the same team that took a series lead in Durban, a match undermined by a series of fractious moments between the teams that came to a head with an off-field confrontation involving Australia's David Warner and South Africa's Quinton de Kock. Those two players were fined and given disciplinary sanctions for their misbehavior, but will both play in Port Elizabeth.
Australia spin bowler Nathan Lyon was also fined for an over-zealous celebration in the first test but also will play in the second test.
South Africa made one change to its 11 in an effort to get back into the four-test series, with fast bowler Lungi Ngidi coming in for Morne Morkel.