The Proteas head into the match with only a share of the spoils available to them after a thumping 239-run defeat in the third Test at The Oval left then 2-1 down with just one to play.
A tour that started back in mid-May has already seen South Africa lose one-day international and Twenty20 series to England, with the Proteas suffering a disappointing first- round exit in the Champions Trophy as well during their time in England.
In their past 19 series they've won 13, drawn five and lost just one -- in India in 2015/16.
But if they are to triumph at Old Trafford -- a ground where their lone Test win in eight visits came back in 1955 -- they will surely need an improved showing from their top order.
For all that South Africa were handicapped at The Oval by the stomach illness suffered by key seamer Vernon Philander, being bowled out for just 175 in their first innings put them at a disadvantage they were never able to overcome in the rest of the match.
England still won by 239 runs but du Plessis believes left-handed opener Elgar's innings has set a timely example.
"Hopefully the batters can respond well because he showed us how you need to bat in Test match cricket," he said.
"We will try to make sure that we can do exactly what he did in the last Test," added du Plessis, who played at Old Trafford for county side Lancashire.
South Africa will look to Hashim Amla for a big contribution after the star batsman twice fell cheaply to England debutant seamer Toby Roland-Jones in south London.
- England balance -
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Yet with Ali, a frontline county batsman, coming in at No 8, England coach Trevor Bayliss is still not sure his side have got the balance right.
Ben Stokes made a valuable century in the middle order at The Oval and Bayliss, with an Ashes tour on the horizon, said: "I'm still of the view we don't need more than seven batters."
But quite how the Australian removes a 'spare' batsman from his XI at Old Trafford is an intriguing question.
Tom Westley made a fifty on debut at The Oval in at No 3, so it would be surprising if he was promoted to open alongside Essex team-mate Cook.
Liam Dawson remains in the squad after featuring in the first two Tests, but quite how England recall the Hampshire left-arm spinner, unless they think the Old Trafford pitch will take sharp turn, is hard to see.
Since 2000, England have won eight and lost just one of 12 Tests at Old Trafford, a ground that shares its name with Manchester United's nearby stadium.
"We've not done things by halves so far in this series," said England captain Joe Root.
"It's just important that we take (with us) the way we've played (at The Oval) -- especially the way we batted, which I thought was exceptional.
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