England 68 for 3 (Root 19*, Bairstow 1*) trail Australia 263 (Marsh 118, Wood 5-34) by 195 runs
Wood, back in the side after concerns about his fitness, bowled with sustained pace and hostility to claim his first five-wicket haul in a home Test, and helped England clean up the Australia innings with alacrity after an unheralded scene-stealing performance from Marsh had threatened to take the game away.
Marsh was a surprise selection in the Australia XI, after Cameron Green picked up a minor hamstring strain, and playing his first Test since the final match of the 2019 Ashes. He had only made four first-class appearances in the intervening period, but produced a bullocking, 102-ball hundred - his third in Tests and third against England - to help steer Australia away from the rocks at 85 for 4 just before lunch.
Marsh dominated his stand of 155 with Travis Head, outscoring his partner by almost four to one, but England hit back to take the last six Australia wickets for 23 runs in the space of 8.4 overs. The game continued to rattle along thereafter, too, as England lost their top three before the close.
England came into this match 2-0 behind in the series and nursing their grievances after narrow defeats at Edgbaston and Lord's. Only a win in Leeds will suffice if they are to keep their attempts to win the Ashes alive - and only Don Bradman's 1936-37 Australians have successfully come back from such a position against their oldest rivals.
There were immediate signs of pace and carry for the seamers, in contrast to the surfaces for the opening two Tests, and England's reshaped attack were soon making further inroads. Wood had not played a Test since December or bowled in competitive match since mid-April at the IPL but hit his straps from the outset, pushing the speed gun up to 96.5mph/155kph and leaving Marnus Labuschagne groping for the ball during three consecutive maidens.
When Labuschagne managed to get off strike, that left Usman Khawaja in the firing line. Five balls that were short or short of a good length were followed by a fuller, 95mph/152kph delivery that beat Khawaja's flat-footed drive and left leg stump flat on the ground. His opening spell of 4-3-2-1 was proof plenty that Wood was ready to blast off.
Labuschagne had grafted for more than hour but eventually fell for a ponderous 21 when Chris Woakes - this was his first Test appearance since March 2022 - had him edging to slip, and England went in to lunch in buoyant mood when Steven Smith, in his 100th Test, fell to a catch at the wicket off Broad despite reviewing Kumar Dharmasena's on-field decision.
It could have been better for the hosts, and dropped catches were a major blight on England's day. Jonny Bairstow missed a tough chance off Smith on 4 and then put down a far simpler chance down the leg side when Head had made 9. The worst aberration was to come at the start of the afternoon session, however, when Woakes found Marsh's outside edge only for Joe Root to grass a straightforward take at first slip.
Marsh was on 12, having smashed Woakes for six earlier in the over, and he fully capitalised on his good fortune in one of the more extraordinary Ashes hundreds of recent memory. Strong on the drive through the covers and down the ground, he showcased his power with a bludgeoned six off Wood that flew into the Western Terrace, racking up his first Test fifty since March 2018 - from just 59 balls - to push England back.
But as the day threatened to run away from them, England grabbed on to Marsh's coattails at the vital moment, Woakes finding an inside edge that ballooned to slip on the brink of tea. And although Root put down another chance to reprieve Alex Carey after the interval, he held Head's outside edge from the very next ball and Wood then tore through the tail in the space of 14 deliveries: Mitchell Starc and Pat Cummins pinned by pace, Carey hit on the head and then holing out, Todd Murphy dragging into his stumps.
There was still more than an hour and a half left in the evening session, and Australia made use of the conditions themselves as Cummins struck twice in his opening spell. Ben Duckett was well held by the leaping Carey - who clinched an outstanding catch by pressing the ball to his lips in the tips of his gloves - and Harry Brook's first outing at No. 3 was short-lived as he edged to second slip.
Marsh then capped his day in the Yorkshire sun by removing Zak Crawley in his second over, via another fiddle to the cordon, before the local pairing of Root and Bairstow throttled down to see out a high-octane day, with the promise of more to come.
Alan Gardner is a deputy editor at ESPNcricinfo. @alanroderick