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.