LONDON, ENGLAND - June 12: Joe Root of England hits out during day one of 1st Investec Test match between England and Sri Lanka at Lord's Cricket Ground on June 12, 2014 in London, England. (Photo by Tom Shaw/Getty Images)

England kept Sri Lanka at bay after losing dangerman Ian Bell in the first Test at Lord's on Thursday.

England, after losing the toss, were 195 for four at tea on the first day with Bell having fallen early in the second session for 56.

But Joe Root and debutant Mooen Ali, both 43 not out, repelled Sri Lanka with an unbroken fifth-wicket stand so far worth 75.

England had struggled to 98 for three at lunch after debutant opener Sam Robson, captain Alastair Cook and Gary Ballance had all fallen cheaply in the morning session.

But Bell, in his 99th Test, was unbeaten on 41 and looking in excellent touch.

Shortly after lunch, he drove left-arm spinner Rangana Herath for six to complete a 69-ball fifty also including seven fours.

But he was out soon afterwards when, hitting across the line, he was lbw to seamer Shaminda Eranga although Sri Lanka had to challenge Australian umpire Paul Reiffel's original not out decision before Bell was finally on his way.

Ali, one of three debutants in the England side, began cautiously but the left-hander found his form in slog-sweeping Herath for six.

Earlier, Sri Lanka captain Angelo Mathews won the toss and elected to field in the first of this two-match series against an England side playing their first Test since suffering a 281-run defeat by Australia in Sydney that condemned them to a 5-0 Ashes loss in January.

Although the sunny blue skies above Lord's suggested ideal batting conditions, the pitch was a greener-looking one than usually associated with the 'home of cricket' at this time of year.

Mathews's decision yielded a quick reward as England lost both their openers inside the first half hour.

Australia-born Robson, playing on his Middlesex home ground, fell for one when he was drawn forward by a full-length Nuwan Pradeep delivery that took the outside edge and wicketkeeper Prasanna Jayawardene, diving to his right, held a fine catch.

And 14 for one became 22 for two when Cook exited for 17, the left-hander bottom-edging an intended cut off Nuwan Kulasekara into his stumps.

Ballance, promoted to number three in only his second Test, was on one as Bell, taking over the number four slot from the exiled Kevin Pietersen, walked in.

Bell demonstrated his class by easing first-change Eranga through the covers for four with a textbook drive.

And the Warwickshire batsman also dealt well with Mathews, Sri Lanka's fourth seamer, by cover-driving and straight driving the all-rounder for elegant boundaries.

Ballance looked less assured but the Zimbabwe-born left-hander brought up a fifty stand with Bell when he clipped Pradeep off his pads for four.

However, Ballance's 73-minute innings ended when, to Pradeep's fifth ball back, he drove flat-footedly and was caught behind for 23 to leave England 74 for three.