Steven Smith continued his rich vein of form by passing his previous highest Test score of 215 to reach the close on 229 not out. He became the fifth Australia captain to score an Ashes double-hundred, joining Don Bradman, Allan Border, Bob Simpson and Billy Murdoch. Smith also became the fourth batsman to score more than one double-hundred in Ashes cricket, matching Simpson's tally of two, with Wally Hammond (4) and Bradman (8) still ahead of him. This was also the first double-hundred in a home Ashes Test for Australia since Justin Langer made 250 in 2002-03 at Melbourne. Smith now has 416 runs from four innings in this series so far. David Malan is the next highest scorer with 248 runs.
The Smith and Marsh show
Mitchell Marsh and Steven Smith added an unbeaten 301 runs for the fifth wicket - the first 300-plus partnership for Australia in Ashes cricket since Michael Hussey and Brad Haddin added 307 at Brisbane in 2010-11. This was also Australia's sixth fifth-wicket partnership of over 300 in Tests. Incidentally it was only the third instance in Test history in which both teams have had a double-century stand for the fifth wicket. The previous two instances were between Sri Lanka and Bangladesh at Galle in 2013 and West Indies and England in 2009. The aggregate runs added for the fifth wicket in the first two innings is also the highest ever in Tests. Australia lost just one wicket in the whole day's play - the last time they achieved that feat was against England at Lord's in 2015. Smith made a double century in that game as well.
Mitchell Marsh made his first century in his 22nd Test. He remained unbeaten at the close on 181, which is his second-highest score in first-class cricket, behind his 211 against India A in 2014. The last Australian batsmen to make a Test hundred at No.6 at the WACA were Doug Walters and Ricky Ponting, and the previous batsman from Australia to get their maiden Test hundred in a WACA Ashes Test was Greg Chappell. Before today, the highest score Marsh had made was 87 against Pakistan at Abu Dhabi.
Quickest to 22 hundreds
Smith scored his second century of the series and his 22nd of his career. In getting there in 108 innings, Smith became the third quickest to this feat behind Bradman (58) and Sunil Gavaskar (101). Smith has scored five centuries in 2017 - the joint-most alongside Dean Elgar and Virat Kohli. Smith now has scored a minimum of four centuries in each of the last four calendar years. Since January 2014, only Kohli has more scores in excess of 150 than Smith. Joe Root and Kane Williamson have made five each. Smith also ended up scoring the highest score in an Ashes Test at the WACA.