Azhar Ali's second century of the series lifted Pakistan to 299-8 but an overall lead of only 188 runs against Sri Lanka after four days of the third cricket test.

Pakistan collapsed from 276-4, handing back Sri Lanka hope of securing its first test series victory in three years. Sri Lanka, already up 1-0 in the series, could have a shot at victory on Thursday's final day if it can snap up Pakistan's last two wickets quickly in the morning.

Ali, who made a century in the drawn second test, scored 136 off 284 balls with 13 fours and featured in two productive partnerships - adding 94 with opener Mohammad Hafeez (52) and another 100 with Asad Shafiq (55 not out).

Dilhara Fernando (3-65) had Ali caught behind with the second new ball and then trapped Mohammad Sami lbw for his 100th wicket in tests.

But the pick of the Sri Lanka bowlers was left-arm spinner Rangana Herath with 4-64 that included the key wickets of Younis Khan (19) and captain Misbah-ul-Haq (5).

Still at the crease at stumps were Shafiq, who made a half century in Pakistan's first innings of 226, and Adnan Akmal, who was yet to score. Akmal has a hairline fracture on his left ring finger, and he'll have to brave the pain to stretch Pakistan's lead on Thursday.

Pakistan's lead was just 65 when Herath removed the experienced Khan and Misbah after lunch. But Ali and Shafiq added a century stand for the fifth wicket and even survived the first hour after tea when Sri Lanka took the second new ball.

Ali completed his fourth test century off 214 balls with nine fours shortly after tea when he drove Herath to cover for two runs. Fernando finally got the much needed breakthrough when Ali played a loose shot and edged to wicketkeeper Prasanna Jayawardene.

Herath then claimed the wickets of Umar Gul (3) and Saeed Ajmal (5), after which Pakistan fended off the last 21 balls to stumps without scoring.

Earlier, resuming at the overnight 27-1, Hafeez and Azhar were rarely troubled by Sri Lanka's seamers as the sun took much of the life out of the pitch in the first session.

Hafeez pulled and drove with ease after watchfully negotiating the first hour with Ali, while both intelligently used their feet against Herath.

Hafeez completed his half century off 93 balls with six fours but played a loose drive off Fernando and was caught by the lone slip.

The pair had come together late Tuesday when Taufeeq Umar (4) was contentiously given out leg before off a Nuwan Kulasekera delivery that pitched outside leg stump.

Sri Lanka missed an opportunity to dismiss Khan with Pakistan leading by 24 runs just after lunch when wicketkeeper Prasanna Jayawardene dived to his right but dropped a low catch off seamer Angelo Mathews.

However, the chance did not cost the home team much when Tharanga Paranavitana picked up a good reflex catch at silly point to dismiss Khan.

Misbah - better known for his slow starts - chose to attack the Sri Lankan bowlers from the outset and eventually paid the price when he tried to drive Herath and got a thick edge to his counterpart Mahela Jayawardene in the slip.

Sri Lanka won the first test by 209 runs at Galle before a placid wicket at Sinhalese Sports Club in Colombo produced a draw.

- AP