Younis Khan scored a triple century to help Pakistan post 574 for five at close on the fourth day of the first Test against Sri Lanka in Karachi on Tuesday.
The hosts are now just 70 runs adrift of the visitors' first innings score.
The Pakistan captain, who was unbeaten on 243 at the tea-break, reached the milestone of 300 runs with a reverse sweep of Muthiah Muralitharan.
He finished the day unbeaten on 306. His innings was replete with 27 fours and four sixes.
It was the third instance of a Pakistani batsman scoring a triple century in Test cricket -- after former captains Hanif Mohammad and Inzamam-ul Haq -- and the 23rd in international cricket.
Sri Lanka, who amassed 644 for seven declared in their innings, were frustrated by a pitch getting flatter by the day.
Younis, 31 and playing in his 59th Test, also passed the 5,000 Test runs milestone in the last session, becoming the fastest of five Pakistanis to reach the mark by surpassing Javed Miandad's record of 65 matches.
The right-hander's effort matched that of his Sri Lankan counterpart, Mahela Jayawardene, who hit 240 in the tourists' innings.
Younis, leading Pakistan in a Test for the fifth time, had earlier on the second day registered his 16th Test hundred, his fourth against Sri Lanka in 11 Tests.
