(CNN) -- Pakistan captain Younus Khan has Brian Lara's world record Test score in his sights after ending the fourth day against Sri Lanka unbeaten on 306 in Karachi.
Skipper Younus celebrates becoming only the third Pakistani to crack a triple-century in the Test arena.
Former West Indies skipper Lara lashed England's bowlers for 400 not out at Antigua in 2004 and Younus has set himself a limit of around 40 overs to try to eclipse that mark.
The first Test is heading for a draw with Pakistan starting the final sessions on 574 for five wickets in reply to the tourists 644-7 declared.
Younus has been at the crease for 12 hours and 11 minutes, hitting 27 fours and four sixes in his bid to rewrite the record books.
He became only the third Pakistani batsman behind Hanif Mohammad and Inzamam-ul-Haq to hit a triple century in Test cricket and needs another 32 to overhaul Hanif's national best 337 scored against the West Indies in 1958.
Next target is Lara's world Test best and the 31-year-old Younus told media: "I have a plan to bat for around 40 overs on Wednesday and see if I could get there but my team plan comes first and for that I would want my bowlers to get some workout."
Younus's previous best of 267 came against India in the Bangalore Tests four years ago and he added: "I dedicate this triple hundred to to my friends, my team-mates and, above all, to my family who have gone through various problems in the last few years."
Younus was involved in two resolute stands of 130 for the fourth wicket with Misbah-ul-Haq (42) and another 174 for the next with Faisal Iqbal (57) as Sri Lankan bowlers toiled on a flat National Stadium pitch.
When Younus reached 184, he completed 5,000 runs in his 59th Test, becoming the sixth Pakistani batsmen to achieve the tally.
Younus also matched Sri Lankan captain Mahela Jayawardene who scored 240 in Sri Lanka's huge total -- the first time in Test cricket's 132-year history that rival captains have scored double hundreds in the same match.
"I jokingly told Mahela that I want to score one run more than him," said Younus who reverse-swept off-spinner Muttiah Muralitharan towards third man to cross the 300-mark.
The second Test starts in Lahore on Sunday.