UPDATE 1-Cricket-Sangakkara gives Sri Lanka chance of record win

* Sri Lanka set to save third test

* Hosts have outside chance of completing record run chase

* Skipper Sangakkara leads way with defiant century

(updates at tea)

COLOMBO, July 24 (Reuters) - Kumar Sangakkara scored a defiant unbeaten century to give Sri Lanka an outside chance of completing a world record run chase in the third test against Pakistan on Friday as the hosts reached tea on 338 for four.

Chasing 492 for victory, Sri Lanka need a further 154 runs in the final session of the match but the home side's initial focus will remain on trying to avoid defeat despite having already secured the series with victories in Galle and Colombo.

The highest successful fourth innings run chase is the 418-7 scored by the West Indies in May 2003 to overhaul Australia in Antigua.

Sri Lanka resumed the final day on 183-3 and added 155 runs for the loss of just one wicket in the opening two sessions when Thilan Samaraweera fell for a well-crafted 73.

Captain Sangakkara led from the front with a determined 111 from 241 balls, including seven boundaries, and the superb century was his first as skipper and the 19th of his career.

The 31-year-old left-hander, who was dropped by Pakistan on 40 the previous evening, shared a 122-run fourth-wicket stand with Samaraweera, Sri Lanka's highest partnership in the series.

At the tea interval, all rounder Angelo Mathews was unbeaten on 33, having helped Sangakkara add 61 for the fifth wicket.

Pakistan's bowlers, who struggled on what remains a flat even-paced pitch, finally broke through after lunch when off spinner Saeed Ajmal had Samaraweera caught behind.

Leg spinner Danish Kaneria, the most threatening of the Pakistan bowlers in this test match, finished with 2-111 from 32 overs. (Editing by John O'Brien; To query or comment on this story email sportsfeedback@thomsonreuters.com)