Joe Root's masterful unbeaten 168 has put England in firm control of the first test against Sri Lanka as they closed a rain-hit second day on 320 for four, a first innings lead of 185 over their struggling hosts.

It has been by no means plain sailing on a pitch with prodigious turn, but Roots skill in scoring all around the wicket secured him an 18th test century and he will resume on the third morning with Jos Buttler (7 not out).

Only 53 overs were possible on the second day, with none at all after tea, but they were enough for the tourists to move into what looks an unassailable position.

Root, whose score is the highest for England in Sri Lanka, already has one double-century against the sub-continent side after scoring 200 not out at Lord's in 2014.

It is one of three he has to date and he will be eyeing another on the third morning.

He put on a superb fourth wicket stand of 173 with debutant Dan Lawrence, who attacked the bowling in an attractive innings of 73.

Lawrence was out as he fended at a delivery that reared off a length from spinner Dilruwan Perera and was caught by Kusal Mendis at short-leg.

After the first 70 minutes of the day were lost to rain, the tourists resumed on their overnight 127 for two but Jonny Bairstow was out before he could add to his score of 47.

He prodded forward to a delivery from left-arm spinner Lasith Embuldeniya (3-131) and was snapped up at slip by Mendis. That ended a stand of 114 for the third wicket.

England's lead already looks daunting, especially after the hapless display from the hosts on day one when they were skittled out for 135 after electing to bat first.

Spinner Dom Bess took career best figures of 5-30, aided by some desperately poor strokes from the hosts, and will be even more of a handful in the second innings.