England's Zak Crawley converted his maiden Test hundred into a superb innings of 267 as he shared a record-breaking stand with Jos Buttler on the second day of the series finale against Pakistan at Southampton on Saturday.
At tea, England were 490-5 in their first innings with Buttler unbeaten on 140.
Crawley's innings was the seventh highest maiden hundred in 143 years of Test-match cricket and the 10th highest individual score by any England batsman.
His partnership of 359 with Buttler was also a new England fifth-wicket record in Tests, surpassing the 254 shared by Keith Fletcher and Tony Greig against India at the Brabourne Stadium in Mumbai in February 1973.
It was also the equal sixth-highest stand for any England wicket at this level.
One of the few false shots of his innings saw Crawley, 186 not out at lunch, go to 200 when he edged a four past second slip off teenage paceman Naseem Shah -- his 25th boundary in 331 balls.
The 22-year-old Crawley was the seventh England batsman to turn his maiden Test hundred into a double century and the first since Rob Key did so against the West Indies at Lord's in 2004.
Earlier, Buttler completed just the second hundred of his 47-match Test career and first as a wicketkeeper.
Crawley, advancing down the pitch, lofted leg-spinner Yasir Shah over long-off for six before a clipped boundary off paceman Mohammad Abbas saw him to 250.
But his near 10-hour innings ended when he was stumped down the legside by Mohammad Rizwan off part-time spinner Asad Shafiq.
Crawley faced 393 balls, hitting 34 fours and one six.
Together with Buttler, he had taken England from 127-4 to 486-5.
England, 1-0 up in a three-match series and needing to avoid defeat at the Ageas Bowl to secure a first series win over Pakistan in a decade, resumed in a commanding position at 332-4.
Crawley was 171 not out, after posting a maiden century at this level in his eighth Test on Friday, with Buttler unbeaten on 87.
- Elegant Crawley -
Buttler, whose 75 at Old Trafford helped England to a three-wicket win in the first Test, had moved into the 90s by the time the first of two rain breaks that halted play for nearly two hours in total.
It took Crawley 25 balls to add to his overnight score but he did so with a stylish flick for four through midwicket off left-arm quick Shaheen Afridi.
Buttler was on 99 when, after wicketkeeper Rizwan came up to the stumps, he was given out caught behind off Abbas.
Buttler immediately reviewed umpire Richard Illingworth's decision and replays showed the ball had missed the bat.
Next ball, Buttler punched Abbas through point to complete a 189-ball hundred with 10 fours and two sixes.
It was the 29-year-old's second century in 47 Tests following his 106 against India at Nottingham's Trent Bridge two years ago -- an innings that took place soon after the World Cup winner's recall to England's red-ball side -- and first as a wicketkeeper.