Michael Vaughan was in awe of Steve Smith's batting as the Australian captain scored his second double hundred in Tests on day three of the third Ashes Test at the iconic WACA in Perth.

Smith became the first Aussie skipper since 1993 to score a double hundred in the Ashes series, which prompted the former England captain to write on Twitter in praise of the current Australian captain.

Allan Border was the last Australian captain to achieve the feat when he hit 200 not out at Leeds in 1993. He also became the first Australian captain since Bob Simpson's 225 against England in 1966 to reach the landmark in Australia.

"In my opinion Virat Kohli is the best player across the three formats. But Steve Smith is the best in Tests. Although I would really like both in the same team," he wrote.

IMO ... @imVkohli is the best player across the 3 formats ... But @stevesmith49 is the best in Tests ... #OnOn #Ashes ... Although I would really like both in the same team .... - Michael Vaughan (@MichaelVaughan) December 16, 2017

He had earlier tweeted saying that Steve Smith has joined Virat Kohli in the freak category.

Just having a glass of vino I have decided Steve Smith has joined @imVkohli in the Freak Category ... an incredible player ... #Justsaying #Ashes - Michael Vaughan (@MichaelVaughan) December 15, 2017

After reaching his 7th hundred against England, Smith ripped off his helmet and raised both arms aloft, pirouetting and waving his bat at his team's dressing room as a big third-day crowd stood and roared in the terraces.

Smith's 17th boundary brought up his 1,000th run for the year, emulating former Australia opener Matthew Hayden by achieving the feat in four consecutive years.

Smith's both Test double centuries have come against the same opponents, having hammered England for 215 at Lord's in the 2015 Ashes series.

Kohli, on the other hand, has scored six double hundreds in Tests and has notched them all up as captain. Like Smith, Kohli also likes leading by example and finished 2017 with 2818 international runs including 1059 in 10 Tests.

Steve Smith currently sits second only behind India's Cheteswar Pujara in the list of most Test runs in the calendar year of 2017. He has scored 1117 runs so far in 10 Tests including four hundreds. During the 2014-15 series between India and Australia, both Smith and Kohli were the leading run-scorers for their teams.

Potentially my most enjoyable day of Test Cricket. @stevesmith49 doing Steve Smith things and a maiden ton for one of my favorites @mitchmarsh235, what a day! #Ashes - Pat Cummins (@patcummins30) December 16, 2017

Amazing stuff from @stevesmith49. On another level. And what about Bison @mitchmarsh235, thoroughly deserved! #Ashes - Usman Khawaja (@Uz_Khawaja) December 16, 2017

What a day of cricket today by our boys. @stevesmith49 what else can we say about him (best in the world). Serious knock @mitchmarsh235 I could not be any happier for him, maiden ?? ?????????. 1-346 #boom big day tomorrow. - David Warner (@davidwarner31) December 16, 2017

So incredibly proud of @mitchmarsh235 what an outstanding innings mate! You stood up when your team needed & @stevesmith49 you are a freak!! Great day Australia ????º #ashes #footonthroat - Mitchell Johnson (@MitchJohnson398) December 16, 2017