England 374 (Burns 133, Root 57, Stokes 50) and 13 for 0 need another 385 runs to beat Australia 284 (Smith 144, Broad 5-86) and 487 for 7 dec (Smith 142, Wade 110, Stokes 3-85)
Birmingham: Yet another Ashes century from Australia's Steve Smith, his second of the match, left England facing a huge battle to save the first Test at Edgbaston.
In his first Test since returning from a ban for his part in the ball-tampering saga, the former captain added 142 to his first-innings 144.
With Matthew Wade moving into Smith's slipstream for 110 of his own, Australia took their overnight 124-3 to 487-7 and declared to set England 398 to win.
Chasing such a total is out of the question, but the hosts' survival hopes were boosted by openers Rory Burns and Jason Roy coming through seven overs to close on 13-0.
England will have to bat out the final day if they are to avoid losing an Edgbaston Test for the first time in 11 years.
They must do so on a surface that will offer plenty of assistance to off-spinner Nathan Lyon, who opened the bowling and immediately proved a much greater threat than England's Moeen Ali.
As Moeen was unable to tie up an end and the part-time spinners were expensive, pace bowlers Stuart Broad and Ben Stokes pounded away on a surface giving them little.
They again did so without their leading Test wicket-taker James Anderson because of a calf injury, while Chris Woakes bowled only seven overs, raising fears over his long-standing knee problem.