Root’s seventh Test hundred, from just 118 balls and the fastest ever scored in the first innings of an Ashes series, was the driving force as England recovered from a perilous 43 for three to 343 for seven.
He shared an all-Yorkshire stand of 153 with Gary Ballance (61), and throughout helped England make good on their new commitment to an aggressive game plan as he and Ben Stokes (52) then took further toll of an off-colour Australia attack in a partnership of 84.
After Alastair Cook had chosen to bat on a cloudy morning, only to be the second of the early departures, Root survived nervous initial moments against his former county team-mate Mitchell Starc (three for 84) but was soon cashing in as conditions eased under ever sunnier skies.
The majority of his 17 fours were pedigree and trademark shots, often eye-catching square and cover-drives – including the one with which he brought up his hundred off Josh Hazlewood (three for 70).
Root (134) was putting behind him a rare double failure in England’s last Test, on his home ground against New Zealand at Leeds, reprising a previous sequence of 11 half-centuries in 18 Test innings.