Stumps England 339 for 9 (Root 186, Buttler 55, Embuldeniya 7-132) trail Sri Lanka 381 (Mathews 110, Dickwella 92, Perera 67, Chandimal 52, Anderson 6-40) by 42 runs
Another stunning knock by Joe Root frustrated Sri Lanka on the third day of the second Test at Galle, but his fall right on stumps swung the contest back in the home side's favour.
Root's near-flawless 186 sent England to the close still 42 runs adrift after Lasith Embuldeniya claimed seven wickets with his left-arm spin that bamboozled almost everyone, except Root.
It was testament to Root's exertions that he fell in gut-wrenching fashion in the last moments of the day, unable to drag his exhausted, cramping body back into his crease in time after nudging Dilruwan Perera to short leg, where Oshada Fernando fired the ball back onto the stumps with an excellent throw.
As James Anderson had said on the second evening, you're never too old to improve or too experienced to learn. And as he, Root and Jos Buttler lived that adage as the stand-out performers in a battling England effort in this match so far, the young and inexperienced members of the squad could learn a thing or two from them.
On the third day it was Root and, to a lesser extent, Buttler who set the example for the likes of Dom Sibley, Zak Crawley and Dan Lawrence upon whom, as current selection goes, England are looking to build for the future.
Root's innings was a masterclass in playing spin. He made batting look easy when, in fairness to the other batsmen, it clearly wasn't as Embuldeniya spun his way to career-best figures and his third five-wicket haul in just his ninth Test.
Root, player of the match in England's seven-wicket victory in the first Test with a double-ton at the same ground, defied his team's woes with the bat in this match. So strong on the sweep the previous day, when he racked up 67 runs off 77 deliveries, Root continued in the same vein on Sunday, his effortless switch-hit to the boundary off Embuldeniya to move to 87 a case in point.
Embuldeniya broke a century stand between Root and Jonny Bairstow when he had the latter out on review. Bairstow, who resumed on 24, added just four more - a powerful drive off Embuldeniya to the rope at long-on - before he got an inside edge onto his pad, which was collected by Fernando at slip. Initially given not out, UltraEdge revealed a clear spike as the ball passed the bat.
Lawrence, so impressive with fifty on debut in the first Test, fell cheaply to an excellent Embuldeniya delivery from around the wicket which turned sharply and found an outside edge, taken at slip by Lahiru Thirimanne. Up to that point, Embuldeniya had taken all four England wickets to fall, having accounted for openers Sibley and Crawley - both for the third time this series - on Saturday.
Root brought up his 19th Test century by punching a single off Perera to midwicket with Buttler still relatively new at the crease. The pair put on 97 runs together for the fifth wicket, with Buttler contributing 55 before his bizarre dismissal to debutant Ramesh Mendis. Reaching forward to reverse-sweep, Buttler struck the ball directly onto his boot and it looped to Fernando at short leg. It took an umpire review to confirm the dismissal after the soft signal had been not-out on the presumption that the ball hit the ground.
Perera took the second new ball and almost immediately thought he had Sam Curran out lbw, but umpire Kumar Dharmasena turned down the appeal and Curran narrowly survived the DRS on umpire's call.
Curran responded by sending the last ball of Perera's over for a huge six down the ground but Embuldeniya had him out two balls later, edging to Thirimanne at slip, sending England to tea still 129 runs in arrears.
Root was doing his best to keep cramping at bay - understandable given his toil in hot, humid conditions in this match and the last - and he brought up his 150 with a powerful sweep to the boundary off Embuldeniya which epitomised the ability to read the ball and position himself accordingly that had underpinned his fine innings.
Dom Bess provided solid support as Sri Lanka struggled to make the one further breakthrough that would have them eating into England's tail.
Root gave them a chance when he edged through the slips cordon, but Thirimanne didn't get a hand to what would have been a sharp catch.
Bess survived an even later chance when he edged Embuldeniya extremely low towards second slip but replays showed the ball had gone to ground. Embuldeniya had him two balls later, however, Thirimanne taking a more straightforward chance at first slip.
Embuldeniya bagged his seventh wicket when Mark Wood edged to Thirimanne, whose effort leaping high to his left made him the first Sri Lanka fielder to take five catches in a Test innings.
Just as Anderson overcame injury which curtailed his 2019 season and near-constant murmurings about his age to pass 600 Test wickets, just as Buttler thought he was playing his "last game" for England before a pivotal innings against Pakistan last summer, it was just over a year ago that Root scored the most patient of centuries in New Zealand, his first in eight months which turned into a double-hundred, in fact. He then went through 2020 without scoring another Test ton.
Now Root is back in sublime touch, passing Geoffrey Boycott, Kevin Pietersen and David Gower to move into fourth on England's list of leading run-scorers with 8238.
Before this match, Root said he had faith that Sibley and Crawley would emerge stronger from a tough introduction to Asian conditions on their maiden tours to the region. On Sunday, all they had to do was watch and learn.
Valkerie Baynes is a general editor at ESPNcricinfo