How well both Cook and Root batted on the first day of the second Test on Friday, rising to an occasion that England could not afford to mess up after their mistakes at Lord's left them in danger of a seriously damaging Investec series defeat.
And how badly in need of inspiration Pakistan are now after England ended the day on 314 for four and well placed to reach the score of 450-plus that should enable them to dictate terms for the rest of this match.
This was destined to be Cook's and Root's day from the moment the captain won his first toss in five attempts against a Pakistan captain in Misbah-ul-Haq who never seems to lose them.
It was a big one, too, as this is a surprisingly dry surface considering all the rain that has fallen in Manchester and is sure to offer more turn as the match goes on, which would have made batting last against Yasir a hazardous process.
Instead, with England leaving out their own leggie in Adil Rashid, all eyes will be on Moeen Ali when Pakistan's turn comes to bat after Cook and Trevor Bayliss showed their faith by retaining him as their only spinner.
At least Moeen will be able to operate with runs behind him after quite brilliant centuries from Cook and Root that came just when they were most needed from the twin pillars of the England batting line-up.
It was Pakistan who were to make the better start, though.
Mohammad Amir had been given a respectful welcome from the Lord's crowd on his return to the scene of his spot-fixing crime, but now he was greeted with cries of 'no ball!' from sections of the Old Trafford crowd after every ball of his opening over.
Far from putting Amir off, however, it seemed to inspire him and he gave Alex Hales a thorough going over before having him dropped in the gully and then comprehensively bowled with an inswinger in the same over.
Hales struggled against South Africa in his debut Test series and then excelled against the lesser lights of Sri Lanka but is finding life difficult against quality bowling again and will become a worry without a big score soon.
Yet all his dismissal did was clear the stage for the two world-class English batsmen. Cook, in his 50th Test as captain, led the way, playing with a fluency that saw him drive far more regularly than usual and handle Yasir impeccably as he became the dominant figure in a stand of 185 of rare quality with Root.
Only when Cook edged Amir through the vacant fourth slip area in the day's first over did the captain offer anything remotely resembling a chance as he moved inevitably towards his 29th Test century, level with Don Bradman, and his 11th as captain, level with Graham Gooch. He is keeping distinguished company.
Twenty innings had passed since Cook last reached three figures, with that monumental 263 against Pakistan in Abu Dhabi last winter, and when he got to a hundred with a clipped two off Yasir, the captain celebrated with rare gusto.
This clearly meant a lot to Cook, who jumped and punched the air before embracing Root and looking to the heavens while cupping his ear in that private gesture he always makes when reaching a century. The only surprise was that Cook's innings was to end so quickly afterwards as, possibly disturbed by what seemed like an extra over beyond 3.40pm before tea, he was bowled by one that kept low to fall again to Amir.
But if Cook was superb then Root was sublime, eschewing the risky shots that had led to his downfall twice at Lord's and batting with all the authority and quality that Bayliss wanted when he encouraged him to return to No 3. Root has fallen between 50 and 100 no fewer than 11 times since the start of last summer, reaching three figures three times in that spell, but there was to be no anti-climax this time as he moved majestically to an unbeaten 141.
It was a good job England's big two were so superlative because Hales was not the only batsman to waste a golden opportunity to make a big score.
James Vince and Gary Ballance are under pressure to prove themselves in England's fragile middle order and neither did anything to ease concerns about their places on Friday.
Vince produced a carbon-copy of virtually all of his Test innings to date, playing some classy drives before, having been dropped by Younis Khan on six, falling yet again to a loose drive.
Ballance did the hard work again before trying to cut a delivery from Rahat Ali that was far too close to his body and chopping on. So hindsight can tell us England could have played Rashid in place of one of them and not lost anything but at least England fielded something like their best team in this match, with Jimmy Anderson and Ben Stokes returning after the 'messy affair' of Lord's.
Normal English service was resumed on Friday. Better late than never.
