In the freshest England side for some time - with three debutants in Chris Jordan, Moeen Ali and Sam Robson - it was two players returning to action that gave the home side control at the close on 344 for five. Matt Prior kept Root company at the crease and walked off with the younger man after scoring 76 not out.
Both men had flopped in the winter and were dropped at the end of the 5-0 Ashes whitewash, but there was no sign of lack of confidence from either player. "It was tough winter, not just on a personal front but as a team so it's obviously pleasing," Root said. "I enjoy playing here. You can't beat the first Test of the summer at Lord's and the atmosphere was fantastic. Hopefully Matty and I can kick on now and get towards 400 if not more."
Prior ended the day close to his attacking best but not before surviving an agonisingly close lbw appeal when he was yet to score. On such let-offs - via Hawkeye's 'umpire's call' margin for error - are careers revived.
Runs here will have cooled the calls for Jos Buttler to be given the wicketkeeping position and Root, for one, is glad. "I love batting with Matty," he said. "He's a great bloke to have in the side and to play how he has is testament to his character and quality. You can see by the celebration for his 50 how much it means to him."
It was the early failures of both openers, captain Alastair Cook and Robson, which put the onus on England to dig themselves out of trouble. A pitch tinged a suspicious shade of green persuaded Angelo Mathews to bowl first, despite sunny skies, and the new ball mostly swung rather than seamed for Nuwan Pradeep and Nuwan Kulasekara. Robson was first to go, misjudging Pradeep's swing down the slope from the nursery end and edging behind. Cook's attempt to cut Kulasekara drew an inside edge.
Gary Ballance and Ian Bell, in new positions at three and four, faced a challenge to rebuild. They fared well until Ballance edged an attempted off-drive from deep in his crease to become Pradeep's second caught-behind victim. Bell added 46 with Root before Shaminda Eranga beat his forward push, hit him in front and then overturned Paul Reiffel's initial not-out lbw verdict.
Ali just missed out on a debut Test half-century, attempting to smack Herath over the ropes and edging to slip. It was the last wicket to fall, much to England's relief.