A match truly in the balance.
England head into day five of the Adelaide day-night Ashes Test four wickets down and needing 178 runs to win after being set a target of 354.
Achieve that and they make history. Here's why.
Should England end the second Test as winners, they will have completed the national side's highest ever fourth-innings run chase in Test matches, which shows the size of the challenge awaiting them on day five.
Currently, that honour rests with the England side of 1928, who chased down 332 to win the third Test at the MCG and take a 3-0 lead in the overall Ashes series.
The tourists went on to record a 4-1 series victory.
Heading to bed 176/4, Joe Root and co will need to score the same number of runs again plus a couple to write themselves into the history books.
Tough? Of course. But that's what Ashes cricket is all about!
Where would a win stand in the overall scheme of things?
First – and most important – an England win in Adelaide would level the series at 1-1 heading into the third Test, which starts on 14 December at the WACA, Perth.
In a wider sense, the result would be the tenth-highest successful run-chase in Test history. No small feat.
If Australia lose this Test, Steve Smith will join South African Dudley Nourse in 1950 as the only captain to lose a Test match having decided to not enforce the follow-on.
Keep up to date with the action on the final day via our Ashes match centre.
Follow all of the team news and results during the Ashes in our dedicated England Men section.