South Africa set England an almost insurmountable 474 to win the second test after declaring its second innings on 343-9.
England saw out four testing overs before stumps to be 1 -0, but has two full days left to survive if it is to save the match and preserve its 1-0 lead in the four-test series.
Never mind that England would set a world record for the highest fourth-innings score to win a test, it also needs to make the biggest fourth-innings score ever at Trent Bridge.
Only once, New Zealand in 1973, has a team made over 400 in the final innings at Nottingham.
South Africa's big lead was built on second-innings half-centuries by opener Dean Elgar (80), Hashim Amla (87) and captain Faf du Plessis (63), who is on course to lead his team to a series-levelling victory on his return after missing the defeat at Lord's for the birth of his first child.
South Africa also had some fun at the back end of its second innings as the declaration approached in the late afternoon, with Vernon Philander (42) and Morne Morkel (17 not out) given license to swing at anything in a final hurrah.
Morkel connected for three fours and Philander heaved Moeen Ali away for two big sixes off successive balls before falling caught and bowled to the spinner.
Ali finished with 4-78 to lead England's bowling effort but the Day 3 pitch didn't offer the same pronounced swing and seam movement for the quick bowlers as it did in the early stages of this test.
Instead, there were signs late in the day of uneven bounce as the surface wears away.
Elgar and Amla, continuing their partnership from Day 2, put on 135 for the first wicket in a stand that wasn't flashy but ground down England's bowlers and ensured South Africa held the upper hand from the start of the day onward.