Younis Khan is on course to break Brian Lara's world record Test score after cruising past 300 against Sri Lanka today.

The Pakistan batsman will return to the crease at Karachi's National Stadium tomorrow unbeaten on 306 and with all of the final day of the First Test to try to better Lara's 400 not out, which was made against England in Antigua five years ago.

With Sri Lanka having soared to 644 for seven declared and Pakistan reaching 574 for five today, there is nothing to play for in terms of trying to force a victory. That means Younis, appointed captain for this series, can set his sights on gathering the 95 tantalising runs he needs to knock Lara off top spot.

The 31-year-old right-hander has already batted for more than two days while facing 545 deliveries from an attack including another world record holder - spinner Muttiah Muralitharan. And he has hit four sixes as well as 27 fours along the way.

Younis, who has played county cricket for Notts and Yorkshire, completed only the 23rd triple century in more than 130 years of Test cricket shortly before close of play today.

Two other Pakistanis - Inzamal-ul-Haq (329) and Hanif Mohammad (337) - are among the 18 players above Younis in a list which includes many of the batting greats of cricket.

Given the scores, the pitch is so flat that even Murali has struggled to make an impression. The bowler with 770 Test victims has struck just once in Karachi while conceding 165 runs from 60 overs. And his fellow spinner, Ajantha Mendis, was equally ineffective on the dead surface, while veteran seamer Chaminda Vaas is still looking for his first success of the Test.

But, just like Lara and all the others above him on the list of high scorers, Younis has had to demonstrate amazing powers of concentration, beginning his marathon innings just before close of play on the second day of the match with Pakistan under pressure at 44 for one

"I dedicate this innings to my family, my friends and my team-mates who have always supported me," said Younis, who has already notched up the highest ever Test score against Sri Lanka.

Both Mahela Jayawardene and Thilan Samaraweera compiled double centuries for the visitors on the opening two days of a match which will soon fade from the memory - unless Younis can turn into an unforgettable event tomorrow.

He is playing his 59th Test and his previous highest score, among 15 earlier centuries, was 267.