Key batsman Steve Smith
The captain resumed on 32, and by the middle session had coasted to his sixth century of the year. While his partner Adam Voges had a couple of lucky escapes there were no comparable nervous moments for Smith. Just as Usman Khawaja had outscored Joe Burns on day one despite scoring fewer boundaries, Smith did the same in his unbeaten 223-run partnership with Voges. West Indies captain Jason Holder used up to five outfielders to stop boundaries. Smith used the resulting gaps well to rotate the strike. The only time he showed a hint of vulnerability - but not much more - came after his century, when he lifted the scoring rate ahead of his declaration. 
Key bowler James Pattinson
The right-armer is still a long way short of regaining the rhythm and consistency expected of him, but when he shows glimpses of it the
West Indies struggle to combat him. He was decent, without being threatening, in the three overs he bowled with the new ball, and then regressed in a two-over spell before tea when he switched to the Members' end he favours in domestic cricket. Even though Nathan Lyon struck after tea and was economical, the captain gave him only four overs to start the final session. The change was rewarded, with Pattinson snaring Rajendra Chandrika and then Marlon Samuels in the first two overs of his spell, and forced replacement Jermaine Blackwood into complete survival mode.
Key moment
When Australia began in the field in the middle session, with Josh Hazlewood and Pattinson, the chant from the former Bay 13 region was instead for "Sidddd-dllle", "Sidddd-dllle". That contingent was left infuriated when the right-armer missed out on a wicket in the 37th over when video umpire Ian Gould ruled Joe Burns' catch of Jermaine Black wood at square-leg may have bounced beforehand. Siddle did not have to wait long for a wicket in almost identical fashion, a flick by Denesh Ramdin off his toes, and then with the next ball he bowled West Indies captain Jason Holder. The crowd was desperate for what would have been the second hat-trick of Siddle career, but that was thwarted by debutant Carlos Brathwaite.
Key numbers
7-1134 The combined score of Australia's only innings so far in the series. Teams need 20 wickets to win a Test, but at this rate the West Indies won't manage it in a three-match series.
1028 Test runs in 2015 for Adam Voges, from 12 Tests. The only player to exceed that in his debut calendar year is Mark Taylor with 1219 in 1989, from one fewer Test.