England 320 for 4 (Root 168*, Lawrence 73) lead Sri Lanka 135 by 185 runs

Joe Root's first Test century since November 2019 has helped England tighten their grip on the second day of the first Test in Galle.

Root went through 2020 without a century - the first time in his Test career he has gone through a full year without one - and dropped out of the top 10 in the ICC's batting rankings in the process.

But here he has provided a demonstration of his enduring class in negating the sharply turning ball with calm authority and moving to his 18th Test century in the process. More importantly, he extended England's lead to 185 with six first-innings wickets still in hand by the time rain returned at tea to bring an early close. Sri Lanka will have to bat substantially better than they managed in the first innings if they are to make England bat again.

If they require an example of how to go about things, they could do far worse than emulate Root. With his judgement of when to go forward and back, his ability to manoeuvre the ball into gaps and his ability to sweep both in front and behind square, he has provided a masterclass in playing spin bowling. Kusal Mendis, at short leg, took so many blows, you suspect a boxing referee might have suggested he had taken enough punishment. Never has Root scored so many runs in a single innings from the sweep.

It was Root's eighth score of 150 or more in Test cricket and the highest score made by an England player in a Test in Sri Lanka. The previous highest was Kevin Pietersen's 151 made in Colombo in 2012.

Root was given assured support from debutant Dan Lawrence. The pair added 173 in 43.1 overs - England's highest-ever stand in Tests in Sri Lanka - for the fourth wicket, with Lawrence losing little by comparison.

Indeed, were you to put together a highlights package of the day, it would be Lawrence's strokes that dominated. There were cuts, drives, sweeps and, shortly before lunch, he launched Lasith Embuldeniya for a slog-swept six that would have pleased Pietersen or AB de Villiers, the men his father told the BBC he idolised growing up. All in all, it suggested England might just have found a man with the character and skill to flourish at this level. Sterner tests loom, no doubt, but this was an accomplished first international innings from Lawrence.

To be fair, Root's innings was not the sort to be accurately represented by a highlights package. 72 of his runs have come in singles, after all. But while those runs might not have made the immediate impression of Lawrence's six, his ability to find the gaps and rotate the strike make him desperately tough to contain. He looked hungry, patient and technically excellent.

While Lawrence was not able to emulate the achievement of Ben Foakes, who made a century on debut here in 2018, this was a hugely promising start from the 23-year-old. Getting off the mark first ball, Lawrence looked confident from the off and, picking up the length nicely, was comfortable to skip down the pitch or go deep into his crease when required.

He did provide one chance. Appearing to lose concentration for a moment, he skipped down the pitch to Embuldeniya when he had 68 and was fortunate to see the keeper, Niroshan Dickwella, parry the ball past the slips. A short while later, he received one from Dilruwan Perera which spat off the surface, took his glove and ballooned to short-leg. It was a disappointment for Lawrence, of course, but England will have noted the signs of deterioration in the surface with interest.

Root and Lawrence were helped, it does have to be said, by some loose bowling. While Embuldeniya - who took the first three wickets to fall - continued to ask questions of the batsmen, he lacked the support required to build pressure. Perera, in particular, has struggled with his line and length - a floated full toss allowed Lawrence to ease his second delivery through the covers for four - allowing England to pick up regular singles.

The legspinner, Wanindu Hasaranga, was no better. Lawrence was able to cut, sweep and drive him for boundaries as he struggled with his length. Hasaranga has conceded more than four-an-over so far; in a low-scoring game, it is a cost Sri Lanka can ill afford.

To be fair to the bowlers, when you have Root's range of strokes - his ability to find the gaps, in particular - it can be hard to find answers. But the fact that there were only eight maiden overs in the innings (and only three on the second day), reflects both the excellence of the batting and the lack of discipline in the bowling. To have hit 'only' 12 fours - 10 of them on the leg side - but still have a strike rate of 66.14 runs per 100 balls, underlines Root's method: it's maybe not as eye-catching as soon, but it is mightily effective.

Earlier, play was delayed by 70 minutes due to rain. When the resumption eventually came, Jonny Bairstow fell in the second over of the day without adding to his overnight score. While Bairstow may reflect he could have left the ball, Embuldeniya had drawn him forward nicely and gained sharp turn to take the outside edge. Mendis also did well to cling on to a sharp, low catch.

At that stage, Sri Lanka still held a narrow first-innings innings. But Root and Lawrence crushed any hopes the home side may have had of making deeper inroads into the England innings. Even the rain that returned at tea to wash out the final session only delayed Sri Lanka's pain.

George Dobell is a senior correspondent at ESPNcricinfo