Bairstow (72no), playing only because England dropped the mercurial Pietersen over his text-message faux pas and ongoing contract wrangles, demonstrated skill and resolution in a maiden Test 50 as he and Ian Bell (58) shared a crucial century stand in England’s 208 for five by stumps on day two.
The pair joined forces against an unrelenting South Africa attack, in full flow, after England faltered to 54 for four in reply to 309 all out.
Bairstow is returning here for his fourth Test – the same number his late father David played – after an awkward start to his career at the highest level against West Indies earlier this summer.
By making the highest score of this intriguing contest so far, he duly illustrated beyond doubt that, even in direct comparison with Pietersen, he is anything but a weak link.
The 22-year-old Yorkshireman needed courage to survive a barrage of early short balls from Dale Steyn and Morne Morkel, and then produced a range of shots which put England back in with fair prospects of first-innings parity at least.
The hosts had lost captain Andrew Strauss to the last ball before lunch from Morkel, and soon needed to show all the mettle their opponents did when they lurched to a position of identical vulnerability early yesterday. South Africa came up with a significant fightback then, and Bairstow and Bell did likewise under yesterday’s sunnier skies as they dug in with determination and did not let their concentration slip – until the latter, batting in Pietersen’s habitual number four position, edged Vernon Philander low to third slip.
Strauss, in his landmark 100th Test and 50th as captain on his home ground, was bowled through the gate by Morkel just when it seemed he and Alastair Cook had given their team a sound start.
Morkel has therefore proved Strauss’ downfall nine times in 12 Tests to date, and there was a familiar ring to Jonathan Trott’s dismissal too – the first of two in four balls for Steyn.
This time, Steyn got his man lbw – via DRS, after Kumar Dharmasena initially reprieved Jonathan Trott – and then Alastair Cook ended his increasingly uncomfortable and unconvincing stay when he chased a push-drive and edged to second slip, where Jacques Kallis expertly held on to a sharp chance.
England had lost their top three for just 10 runs either side of lunch – and suddenly, in this match they must win to level the Investec series and hang on to their Test-playing world number one status, they were in trouble.
James Taylor, in only his second Test, edged behind off Morkel to Graeme Smith at first slip – leaving Bell and Bairstow under extreme pressure.
Bairstow needed 13 balls to get off the mark, with a single, and an ultra-watchful Bell took 41 deliveries to reach double-figures with a clip to midwicket for his first four in the same Kallis over.
Bairstow was always batting at a slightly quicker tempo, bringing up his 86-ball 50 in fortunate fashion with an edge at catchable height just wide of the slips for four off Morkel.
Three of his eight boundaries to that point had come in calculated leg-side attack in the same over from leg-spinner Imran Tahir, as he and Bell cashed in on their own hard work.