An unbeaten 72 from Jonny Bairstow has given England a slight edge after two days of a fascinating third Test against South Africa at Lord's.
After wrapping up South Africa's first innings for 309, England were 208-5 at the close, largely thanks to a stand of 124 between Bairstow and Ian Bell for the fifth wicket.
The hosts were in deep trouble at 54-4 before the middle order pair came together to frustrate the South African attack for much of the afternoon.
With South Africa resuming their first inning son 262-7 in the morning, England's bowlers had encountered continued resistance in the first hour, courtesy of Vernon Philander (61) in particular.
Stuart Broad saw off Dale Steyn with full-length swing, caught at second slip in the fourth over of the day, and Morne Morkel eventually chased a wide ball from Steven Finn (4-75) and fell to a one-handed diving catch by Matt Prior, the wicketkeeper's fifth of the innings.
But Philander completed his maiden Test half-century before he ran out of partners. By the time he was stumped off Graeme Swann, the tourists' last six wickets had realised 255 runs - a statistic England could yet better, if Bairstow stays the course.
The 22-year-old Yorkshireman - called up to replace Kevin Pietersen in a game England must win to share the series - needed courage to survive a barrage of early short balls from Steyn and Morkel, and then produced a range of shots to haul England back into the contest.
They 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 on day one.
South Africa came up with a significant fightback then, and Bairstow and Bell did likewise as they dug in with determination and concentration - until Bell, batting in Pietersen's number four position, edged Vernon Philander low to third slip.
Strauss, in his 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 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.
Bell's dismissal for 58 prompted fears of a late collapse, but Matt Prior joined Bairstow in playing some agressive shots before the close and the pair will hope to close in on South Africa's total on Saturday morning.