Amir had Alastair Cook (81) badly-dropped twice before finally shifting the England captain in his fourth spell, resuming his Test career at the scene of the 2010 spot-fixing crime that earned him a prison sentence and five-year global ban.
But Yasir (5-64), like Amir on the comeback trail in his first international appearance following a three-month ban for a doping offence last winter, ensured England’s vulnerabilities were exposed as they were reduced to 253-7 in reply to 339.
The leg-spinner soon had the measure of the hosts’ middle order, after Yorkshireman Joe Root’s attempt to dominate him fell flat and ended his century stand with Cook.
After Chris Woakes had finished with a career-best 6-70 on an increasingly cloudy morning, Amir’s first steps back into the spotlight were under the most minute scrutiny.
But apart from a smattering of ironic no-ball calls from the crowd, there was no apparent residual animosity over the brilliant left-armer’s part in the conspiracy which rocked cricket six years ago.
There was no overstep, either, from the bowler who did so to order for financial gain on his last visit.
But it was Amir’s fellow left-armer Rahat Ali who made the only breakthrough in the hour before lunch, Alex Hales caught at third slip pushing forward to one that offered to swing in.
Amir had begun his six-wicket performance here in 2010 by claiming Cook as his first victim and would have done so again, had Mohammad Hafeez not put down a straightforward edge at slip.
Cook, on 22, added an immediate insult to injury by clipping the next ball off his pads for four as he and Root sought a foothold.
They stayed put until beyond mid-afternoon, Root convincing in his new position at No 3 until he spoiled the impression – two short of 50 – with an ugly attempt to slog-sweep Yasir off his length, looping a catch to mid-on.
By then Cook had passed his joint second-fastest Test half-century, with 10 fours from 60 balls, and then edged Amir behind on 55 only for Sarfraz Ahmed to fluff another easy chance.
Yasir was to take two more wickets before tea, though, James Vince and Yorkshire’s Gary Ballance both going lbw.
Vince fell to a variation ball that skidded on, leaving him still searching for his first substantial Test innings, and Ballance’s first attempt at this level since last summer ended prematurely when he pushed forward and missed a leg-break.
Amir returned and was rewarded at last when Cook edged an attempted push-drive on to his stumps, departing with a disappointed waft at what remained of them.
It was over to Yasir again to deceive Yorkshire’s Jonny Bairstow, bowled after picking the wrong ball to cut.
Then Moeen Ali was the victim of some tight geometry when he almost got outside the line sweeping a ball that would very nearly have spun past the stumps – but had to go lbw anyway, on two counts of umpire’s call which put Yasir on the honours board.
Pakistan had earlier resumed on 282-6 and after losing two late wickets to Woakes the previous evening, their last six went for only 57.
Misbah-ul-Haq (114) and Sarfraz threatened to give England a headache, before both went in a burst of three wickets for six runs.
Sarfraz had been advancing to Woakes and Stuart Broad (3-71), and picking them off, but he fell to a soft shot – a cut to point which gave Woakes a treasured fifth wicket.
England’s breakthrough cricketer of the summer celebrated by seeing off Wahab Riaz for a second-ball duck, pushing a full one up the slope to bowl the tailender middle-stump.
That was Amir’s first cue, at No 10, and the Lord’s crowd responded to his name with polite applause, which spoke of apparent, considered goodwill.
His earliest exchanges were eventful, an edge past leg-stump for four first ball off Broad followed by a clonk on the helmet next up.
Amir lost Misbah quickly, undone at the end of his fine 199-ball innings when Broad bowled him on the defence – and after a spirited last-wicket stand with Yasir, it was time finally for the main event.
The surprise was that Amir would, initially at least, play only the bit-part of a luckless stooge.